Counter-Strike is actually one of those instances where DRM adds value to a product for paying customers. Counter-Strike is a very popular target for cheaters using client hacks like like aimbots and transparent wall hacks, and one of the ways to avoid those players is by hiding behind a pay wall. Every time a cheater is caught and banned, the only way for them to get back in is by paying $10 to re-buy the game. Adding DRM to the client ensures that this pay wall remains intact, meaning that cheaters can ruin my multiplayer experience constantly only if they are willing to inject a fair amount of cash into the system (and very few are).
Old battlenet (before SC2) could disable CD keys in multiplayer, and was a level of DRM I'm ok with. People hack, and having a mechanism to ban them made sense. It doesn't have to come with all of the "single account tied to your purchase" or "3 hardware changes" that we're starting to see.
I'm pretty much OK with CD-keys, and I tolerate Steam because it hasn't had serious problems yet, but anything else I tend to distrust.
