It's factually incorrect to say that DRM has not caused lost sales, as certain publishers have relented to some degree.
Exactly that. I have refused, and still refuse, to buy Assassin's Creed (either of them) because of terribly restrictive DRM. So there's a perfect example of DRM causing a lost sale.
And yes, the publisher has the right to put out whatever they want to put out. They can pile on GFWL and Securom and require a CD in the drive and require an always on internet connection and if they see a blip in your internet connection they can force the game to exit and run an automatic uninstaller. This is all technically possible to do.
We as the consumer base reserve the right to refuse to play their intentionally crippled games, and we deserve the right to complain about it. As a lone consumer refusing to buy a game, I can't really effect any change in the system. But if I complain about it every time the subject comes up on forums, I can help change minds and cause more people to refuse to buy these games. That's my tool for changing the system. (Note that I'm not promoting piracy here. The whole point of refusing to buy a game flies out the window if you give up the moral high ground by stealing it.)
And the argument that by buying a game, you waive all rights to complain about the DRM is just nonsensical to me. Each person has to weigh how much they value playing a game versus how much pointless crap they're willing to put up with to play it. Shoddy DRM causing game issues because an internet connection blipped for a few seconds isn't the consumer's fault. They have no say in the matter.
No one at Blizzard is calling up players and asking if they'd like it to work that way. Players put up with it because they have to, because they want the game bad enough that they're willing to ignore it. That doesn't mean they like it, and it absolutely does not mean that they should be expected to like it. The consumer's only choice is to buy the game or not. They may hate the DRM, but they hate the idea of never being able to play the game more. That's fine, that's a personal value judgment that everyone has to make when confronted with this situation. But that doesn't mean that by buying it that they're agreeing that all the DRM on it is great and that they love it. Just that they're grudgingly willing to put up with it. Not remotely the same thing.