Desktop Environments are only programs. They take the user away from the actual OS. I feel that you should understand what an OS is.

However, I'm not against them. They do make things somewhat prettier...but I have a terminal embedded in my desktop, and I use that mainly. I use elinks/w3m, g++, ee, and do all kinds of stuff from the command line. It's my preffered way of navigation.

But, DEs are pretty sexy...add gDesklets and Compiz, and AWN, and ZOMGOrDZ. Cute.