I think this discussion is probably going to go back and forth for the rest of the foreseeable future, because this is just like 'which console you like the most' as DRM/copy protection isn't a technical discussion of dis/advantages but personal preference.
I thought I might as well tell you my story as I was an avid fan of everything Steam, right back from CS1.6 days. I saw Steam then as a matchmaking client more than anything else, it was a convenient method of playing with my friends. Amongst us we slowly got sick of swapping I.P addresses over MSN messenger just so we could play unreal tournament (on dial up) with a 2 second lag. Steam changed that, it was so easy and simple, but I still had sick lag >.<
Slowly over the years, things changed; but it took me a while to accept what digital distribution meant. I bought my first digital copy of a game: CS: Source. It took me so long because I was so used to owning a physical copy of games, but once I had dispensed with the disc, I fell in love with the concept. Ergo I also fell in love with Steam because that's all I knew. All my friends were on it, we got to play together and all was well.
I think for me things changed with the announcement of Rag Doll Kung-Fu, the first non Valve developed game to be put onto steam (I thought so at least - excluding game mods). This, over a short period of time, exploded into a veritable gang-bang of games. I felt rather overwhelmed, I wanted to own everything because that's what I was used to, all the things on Steam were in my account but now I was looking at games I'd never even heard of before. I understood why valve games had to be on Steam, but why couldn't I get these games to download without having to log into a developer's match-making service?
I still wasn't exactly bothered though, as I knew of nothing else, but during a LAN party everything changed.
Myself and six friends all met up to play CS:Source together, but as you might guess we didn't have internet access and the crap really hit the fan. We all legitimately owned CS:S, but had to then waste about three hours just connecting to the net, to turn Steam into off-line mode. Yes, I suppose we should have done our research, but this really got my wick. We all owned our games, but this method of DRM caused massive issues. One friend couldn't even connect to the net for some reason, and so he couldn't even join in on his machine.
At this point forward I started losing interest in Steam, especially when I started thinking, "Is Steam really going to still be around in twenty years?". All those games I owned and paid real money for would be lost; I just got spooked.
As a consumer I decided that I didn't want to sink money into my Steam account any longer, not because I didn't get a physical copy of these games, but because I knew nothing in this world lasts forever. Can anyone really say when their in their eighties they know for sure that they will still be able to log into Steam? I know one thing, I'll still have backed up somewhere my copy of Fallout 2 I downloaded from GOG, and it will run, even if this website goes the way of the dinosaur.
As I said to start, this is to do with personal preference. I prefer games which respect me as a consumer instead of assuming I'm a pirate. I don't know, there is probably a million rebuttals to what I've said, but its just what I believe is right. Copy protection will always be around, but I'm choosing to avoid it as much as possible, and I blame no one or anything for it.