Just thought i'd throw in my 2 cents on two of the matters being discussed here.
1) The issue of STEAM; particularly STEAM being horribly bad and so on.
I've bought games on STEAM before and never really had any issues with it. I personally love it, maybe not so much STEAM itself as any D2D type of "store". I can easily, and quickly purchase a new game without standing in line or having to go out to a store for it, and since my purchase stays active within my STEAM account forever, i can easily install it on another pc, reinstall it 10y later etc, and never worry about losing/misplacing/breaking my cd/dvds.
As mentioned already you can always turn STEAM to offline mode after installing the game, you can also disable auto updates and, at least as far as the games i bought so far, you can easily patch them with patches you manually download and add mods just like normal.
Yes the steam client has to run, as it is overimposed on top of the game like a launcher and community tool (much like the Games for Windows Live platform), but i for one never really had any issues with it.
2) On the whole "using STEAM allowed for a better Civ 5" thing.
Fact is, it did. I used to work in the video games industry. Not for very long mind you, just about 8 months, but i can tell you that games, much like any software product (and possibly any other product) are dependant on 2 things during the development time: TIME and MONEY.
The 2 are interchangeable to a point, but far from 1:1 and you can't always make up a lack of one with more of the other.
In this particular case, Civ5 was (most likely) planned from the start with some form of community tool and multiplayer support.
This represented development time that the devs would've spent on making this part of the game (whether you think it is in fact important or not for the game as a whole does not matter, they were going to add it anyway and it was going to take a certain amount of time)
By using STEAM, they exchanged some MONEY for extra TIME, which they in turn can use to develop other facets of the game (such as AI, Balancing, etc, which most would agree is a good thing).
As such, using STEAM DID in fact help with the development of the game, regardless of whether or not it was ordered by 2k or not.
To conlclude, i feel that, while there are definitely some legitimate concerns about the use of STEAM in the case of civ5, most of the large uproar is coming from misinformed people afraid of something they don't care about researching first.