R00fles! At best it's an 'ok' DRM system, at worse a horrible subscription system that is overrated by most of its users. Oh wait, that's one in the same - it's both DRM and a subscription system! What's there to like again? Oh, the sales. Those are ok... And really the only reason one would use it aside from the games that require it.Some people like the saved game backup services (I wish I had that when I lost my NWN 2 progress), others might like voice chat or just the convenience of managing their digital libraries with one login and one-click installation, especially if you're away or buy a new computer without access to your physical media. I hate having to rummage through boxes trying to find installation discs and license codes and having to carefully enter codes for perhaps dozens of games. Others still might not bother with good backup or record-keeping for non-DRM games they've bought through PayPal for instance.
Steam does make it all pretty easy. So yes there is a lot more than just DRM and as you said, sales like 80% off are great too!
Before I sound too much like a Steam salesman I agree I'm inherently opposed to DRM also. Just do agree that. as with films and TV, hackers find a way around it and all it succeeds in doing is inconveniencing legitimate customers.