I do take issue with Steam's (and retail-bought games using Steam) policy on second-hand games - i.e. once it's registered once, you can't sell it on. It renders the resale value of the game worthless. I can't see how it benefits anyone. And I can almost see the rationale in having a different policy on downloads from Steam - possibly because it is a new delivery method from the established model (where one can sell on second-hand games) - but retail-bought games that require Steam have the same policy, which seems off to me.
There are lots of gamers who will buy at full price. There is also a fair number of gamers who cannot or will not afford full price. Some of these will buy new a few months down the line when the price has dropped a bit, but that leaves a large number of people who would ordinarily buy second-hand but can't because it is 'disallowed', so don't play the game at all.
You might say, "well, that doesn't affect the publishers because they wouldn't have got any money from the second-hand sale anyway", which is true in the short-term at least. But what it also means is that for games with online multiplayer, the number of people online is greatly lessened - when people stop playing their copy, they can no longer sell it on to people who would play it, so there are fewer copies being played in circulation - which may well lessen the online experience. Again, doesn't really affect the publisher directly - but because the game is less-enjoyable, gamers are less likely to buy a sequel. So indirectly, publishers lose out, for the sake of a few more short-term sales.
Coming from a background where it's been commonplace to buy games, play them, and sell them on when bored, I also just plain disagree with the principle that you're spending more and more on new games (over the years), yet you're getting far less out of them in terms of resellability. And surely it's against some free market ideation that you can't sell on a product you've bought?
It's totally different from piracy, for example, where you'd be making a copy of the game and having two or more people play the same game, where the publisher is suffering a much more real loss, as there is demand to play more copies at once than the publisher has sold.