You really don't get any more single player as piracy has killed the market.
Actually, World of Warcraft can be more to blame about that one.
Imagine how console game sales would've dropped if WoW had been available on major consoles when it had it's major boom.
In the real world, Blizzard gets away with it, EA gets away with it, because 99% of the world don't actually care.
I think EA, Valve and Blizzard (among others) get away with their DRM crap because they are big enough and have valuable enough properties that the people who don't care enough can keep them afloat.
I doubt smaller companies, or indies, can afford the backlash that comes with obnoxious DRM.
As for DRM...
In my opinion, as a project's budget grows, there are diminishing returns when investing on DRM, since all
DRM can be defeated, and high-interest products (and high budget usually equals a budget for publicity and thus hype/interest) will be targeted and broken quickly.
I personally would try to achieve a balance between protection and usability. The moment the pirated version of your game is more convenient for the user than the legal version, you've lost.
But, then again, I'm still not dealing with these issues in my projects, so just stating my general opinion.