I basically just wanna mirror the various things that AC10 has said, but add a few of my own that probably aren't worth mentioning, but I'm going to anyways.
I have always been against DRMs, mainly cause I grew up in an age where game we bought were OURS to play as we saw fit. We could own it 10 years, dust it off, and it'd work. DRM based games will very likely be completely useless 10 years down the road unless someone goes to the trouble of making a dedicated server for them which happens with a few old games like Starcraft and some of the older counterstike games. Hell I've played DOOM online and it was kinda fun.
But my point is this, games are getting more and more expensive to purchase, and if I'm told that the 40+ bucks I just spent was JUST for the right to play it and not actually, you know, have it in my hands, etc.. than why bother? I'm not a pirate, but I've certainly considered it. When I bought Spore Galactic Edition and the activation code didn't work, I had to prove to EA that I owned the damn game before I could get another code which was in use by someone else in another state. I can't prove that person pirated anymore than EA could, but I wouldn't be surprise if that person's game was suddenly revoked and they had to go through a process to prove it wasn't.. or they downloaded a crack, which is what I was sorely tempted to do.
I like what GOG does, which is allow me to buy the game and download it whenever I want to, or put it on a disc and take it anywhere. It allows me to buy games I can't play anymore due to computers simply advancing past what they once were. I know that scares the crap outta some designers, but by gods, those days of actually OWNING the game were grand. I could even cheat at it and I wasn't hurting anyone, hell sometimes that made it more fun and would ensure I didn't return it.