tldr: Tough luck. Read it if you want to hear my opinion.
Lately I have seen Steam compared to other services that have a similar or more extreme level of "monitoring" the user. e.g. facebook accounts (and all the associated problems with apps etc.), debit/credit cards, gmail and so on.
The argument goes that anyone opposed to the fact that Steam collects certain data about you (even if not personally identifiable) must necessarily also be against the data collecting done by these other comparable services and so it is (wrongly) implied (as in there is no logical argument!) that such people must not use these other services. The argument is not logical because someone who opposes the data collecting from those other services doesn't necessarily have to discontinue using those services to oppose them. It merely shows they are not concerned about it enough to cancel the service.
Secondly, using a service like gmail as an example (for which I have two accounts of my own), I am prepared to accept there is some data mining/collecting going on (which has $ value to the entity collecting it, even if only a tiny tiny value) because I am being provided a service very cheaply or for free which I actually want. If I didn't like the terms and conditions of gmail accounts, I could have signed up for any number of its competitors like hotmail which to my knowledge would have very similar levels of data collecting. I don't yet know of any non-Google service which requires me to have a gmail account. (I apologise for slightly repeating this point in the next few sentences

)
Now, the reason I find the comparison of Steam to these other services problematic is quite simple. All of these other services provide a service to the user which the user usually actively sought out. Also, the conditions of the service usually only relate to that service and not to the use or purchase of other products. For example, I don't need a gmail account to sign up for civfanatics - that would be an arbitrary and probably annoying requirement for many potential forum members. I don't need a particular credit card to buy something from a store (though it's quite common for some cards not to be accepted). I don't need to have a facebook account to buy any video game I know of (except perhaps a facebook app

).
As a side note, ebay got into a bit of hot water when they attempted to make all transactions necessarily carried out using paypal - a payment service owned by ebay. In effect they wanted to be able to double dip by taking auction fees
and fees from the money transfer. This did not sit well with the ACCC and many of ebay's customers because it essentially fell under restrictive trade practices under Australian law (note, I'm no expert on this!, so don't take my word for it) - that is, restricting payment methods in the way they wanted to. In the end, it was settled that paypal would be a mandatory option to the purchaser - that was considered acceptable.
Now, civ5 is a game that we may purchase (if only the license, whatever) but to use it we need to agree to and use the Steam service - something provided by a separate business entity. That is rather unlike any of the other data collecting services I have seen Steam compared to.
One could argue that Steam or Steamworks provides positive-valued features to the end-user and so that is why we should accept the data collecting that Steam carries out. Personally the only feature I see so far as being valuable to the end-user in the Steamworks package is the MP functionality. I would understand many appreciating the friends-list type feature as well though this is only perceived as a good thing so far by people who already use steam
and have "friends" on it. I see things like the achievements as pointless fluff that is really just distracting the gamer from where the real value is in a game. I would
never suggest a game should use steamworks so it can have achievements, but the other features provided by steamworks I can see as reasonable to want in the game from both the developer/publisher and customers points of view.
I'm not really against Steam. I think it is a useful service and I can see myself using it in the future. I don't usually like the prices on there and I don't care whether it's the publisher who sets the prices or not - if there's a competitor offering a cheaper price for the same product I have no right to complain about the price.
However I don't like the way Firaxis/2K have got into bed with Valve by relying on Steamworks and hence relying on its DRM and almost certainly end up using Valve's purchasable-DLC service, as well as signing a deal to offer an exclusive deluxe edition tied to Steam purchases. Any attempt to spin this as something that civ fans wanted is downright insulting. (However, please correct me if I'm mistaken by linking me to somewhere where fans were calling for both of these things - steamworks and a steam-exclusive special edition - before 2K made the "steam announcement".)
Now, to address a couple of points I think need it...
Privacy is good, avoiding Steam because it lets Valve know how good/bad you are at a video game is silly.
How many of those things does Valve advertise?
Ignoring the fact that your suggestions are so low value and yet requiring quite a sophisticated degree of interpretation and understanding that you'd practically need an AI to understand them as no developed world citizen could do it cheaply enough, how does Valve which advertises no product not on Steam turn that into money?
Your data is safe because your data is worthless. Noone is interested in your personal habits.
(emphasis is mine)
I think you are either mistaken or being misleading by saying things like this. I appreciate you have high qualifications in a scientific discipline but you appear to grossly under-estimate the growing field that is data mining. I don't want to make it a dirty word like so many immediately apply but I won't pretend it's not a big thing in business. There might not be much value to a single user's data by to suggest it has zero value is dishonest. If that were true, then data of the same type but of 1 million users would also have zero value - something which is obviously absurd.
The_J went to the trouble of giving some very specific (and entertaining

) examples of how seemingly boring data can lead to various "guesses" about the user. You seem adamant that this is near impossible to do or irrelevant on an individual-user basis. Why does it have to end there though? If you, for example, observe that younger children respond more to colour in tv commercials, then it would make sense to make fast food ads during kids tv shows use more colour. This sort of thing can easily apply to steam's advertising. Even if the ads on the steam client are completely uniform across every user now, they won't necessarily always be, especially if steam's account numbers continue to grow the way they have. There's nothing necessarily wrong with that either, IMO.
EDIT... Just to clarify, I wanted to say that even if you can't use the data to individualy target ads at users, you can still use the data to target ads at groups of people and achieve a similar objective.
I would argue that part of google's success over the past decade and a bit can be attributed to its employees not being constrained by a narrow view of the world like "X piece of data is worthless, end of story".
Now on the other hand there is quite clearly and obviously a means for valve to turn in game death/achievement/completion information into making a better product. Its relevant, pertinent and unambiguous. You put it into your favorite data analysis package and you get something useful. But note that the outcomes say nothing at all about any of the participants.
Its the same old story, follow the money. Criminals want your credit card, governments want a statement of your annual income, companies want to know why their product sucks, noone wants to know what game John Q. Nerd was playing last night. The very least they'd be interested in is what all the JQNs are playing this past month.
If there is no value to Steam/Valve collecting data about how long you've played games, then why do they even do it? Do you think it was a feature that was implemented because the end-users wanted it? As much as you might ask me, "What reason do you have to object to your game-time being recorded and shown? so your wife doesn't know?", I could equally ask you, "What reason do you have to want your game-time to be recorded and shown to you? Why would you actually care?"
While Steam provides lots of "stuff" to me for free, I also provide a bit of stuff to it for free. I can sympathise with someone who finds whatever stuff Steam gives them to be of little to no value and hence Valve taking free data way from them being a little unfair. Civ5 requiring steam is a tad unfair on those people and the only justification for it is the positive features that steamworks provides - again many of which features those people don't want or care about either.
Final rant: Firaxis and 2K hadn't even thought to include PBEM/hotseat/pitboss functionality at release. This was a big "WTH" moment when I read it. It sounds to me like they've only thought about MP at all very very late in the development process, around the same time as signing the contract with Valve.
