The only DRM I know of that's more unobtrusive is the simple DVD-Check.
Developers need to counter piracy in some way, DRM is that way and it's here to stay whether we like it or not. Right now Steam is by far the best service available, and if you compare it to Ubisoft's draconian new DRM you'll see what I mean.
I don't see how you come to the conclusion that Steam is the best service. It's already been shown that, right now, as we speak, there are people playing illegal copies of Fallout: New Vegas. It patently does not work. Meanwhile there are people with legitimate units waiting to have their games activated. Waiting in line, waiting through Steam errors and busy servers, waiting on Steam to get past the fact it's mistaken a physical install for something that requires a full game download/ People with legit copies having their saves shuffled around and dikeed with.
If it fails as grandly as other DRM, as copy protection, as a bar to piracy, what makes it the best? I think you're confusing services you like that come with Steam, with what it is actually good for when it comes to curbing piracy, and the argument therefore,
FOR Steam. It's good for the services you like, you like them, but it svcks as much as the next DRM, and it svcks for having a complete lack of benefits to people who don't want to use those services. To them, it's just an intrusive piece of software, and in some cases a barrier to playing the game, and beyond those cases, a barrier to playing a game without the hassle of encountering problems that only exist because it is there. :shrug: