For Australian purchasers late last year Civ5 on steam was nearly double the best price at a physical games shop here (something like $89 vs $49).
That happens with pretty much every game that is released in Australia
Please correct me if i'm wrong, but are you really defending a game for 10$ without a box against a game for $10 with a box o_O?
Since you are extremely unlikely to find a boxed game for $10 in most retail stores here, then yes, since it is the better deal. I don't see the problem.
...and on Steam?
Anecdotal evidence, but during the last sale i saw a screaming "80% down" for Divinity 2, down to 10$ (or €, whatever) from normally 49.99.
Awesome deal, isn't it?
Pretty much hides the fact that this game has been for sale in retail shops for 10€ for months now (bought it in August...with a big paper box).
As has been made extremely clear before, retail stores (especially in Europe) seem to be able to set their prices a lot lower (possibly because they need to clear out shelf space and the prices are less directly controlled by the game's publisher) sooner than Steam, but they don't put them on sale for less than $15.
Ten euros is currently ~$13.70 Canadian, but retail stores generally seem to price games in multiples of 5 only (well, minus a few cents of course).
Old game, valued at 40 bucks, mid 90s style:
Mid-90s is the key here, except for The Witcher 2 games including lots of extras have been getting rare for several YEARS! I remember being rather disappointed with Oblivion for coming with just a manual and a paper sleeve for the CD. Though I don't think most people really care about the extras anyway, a good friend of mine keeps giving me the maps and a few other extras from his games and collector's edition whenever he stumbles across them in his closet/storage. Most people seem to lose them or, at the very least, never use them more than once anyway.
-You can resell it, specially for collection purposes.
-You can borrow it and trade it, family members can install the game as well.
Sadly that is becoming less possible these days since used copies sometimes have to pay EA's Project $10 fee for content that only comes with new copies as well as other account based DRM (EA's Origin is starting to copy Steam) and Ubisoft's U-Play bullcrap.
-Most popular multiplayer games had relaxed copyright protection, hence their popularity.
The most popular multiplayer FPS games use Steamworks (Counter Strike, CSS, TF2, CoD: MW2, Blops, MW3) and BF3 uses Origin. Popularity is based more on fun and how many of your friends play it than the DRM.
A new game, valued at 40 bucks, steam style:
If you absolutely must have these then the answer is simple, don't buy a digital copy (especially when new). You're acting like people are saying you should buy all of your games on Steam/digitally, no one is recommending that. The only reason I even have so many digital games is because I paid less than $15 (if not less than $10) for the majority.
-Most popular multiplayer games charge monthly or in micro-transaction form for that honor. So you know, pay up.
Besides map packs I don't see any extra DLCs for many of the most popular multiplayer games (Counter Strike, Call of Duty, Battlefield, etc). The only popular one I can think of that does have microtransactions is TF2, and you can get all of the weapons free from playing the game or trading (and many of them are arguable not that much better if at all than the original weapons).
There is also Battlefield Heroes (doesn't use Steam of course) that is free 2 play and you RENT the weapons and upgrades, no idea how popular it is but it is still going and regularly "updated".
MMOs are the only ones that charge monthly fees and they have their own system set up entirely.