I like Steam, clean interface, loads fast.
However I only have 2 GB of RAM, atleast 500 MB of it of course Windows allocates to itself, there is a limit of how much I can run. Also, I like to run a clean system, fast and responsive. Even once I upgrade with a better system, I do not want programs from Stardock, Activision, 2k Games, Take-Two, Codemasters, Microsoft, Eidos, and Ubisoft running in the background, just so I can play games.
An environment like that will encourage hacked games, something similiar to NO CD patches. Steam is good, but I dont want 2 or more programs like Steam, DONT NEED IT, do not want it.