I have had times when I didn't have the disks around when it was usefull. Also, I prefer not to have to have a disk in the drive to play. And, yes, there are 9 trillion instant messangers, which is why I enjoy having one central one that everyone who plays the games use.
DRM does suck, but Steam gives you a lot of benifits for using it, such as being able to download the game any time, anywhere, on any PC you want, and friends lists. I think the good out weighs the bad in Steam's case.