Steam will make it possible to get games before you could if you ran to the shop and bought them - faster than downloading off Sp1d3rm0nk3ys ftp, faster than having them delivered.
This leads on to valves other upcoming games. I have no doubt that cs:cz, tf2 and cs2 WILL be available through steam.
Just because valve aren't showing off TF2 it doesn't mean they're not working on it. Wait? They're developing steam!? Of course, it's impossible for a comany of valve's size to work on more than one project at a time.
The bottom line is Steam is not a waste of time - it will revolutionise the way we play and buy games. Games will be cheaper for us, the developers will make more money. Everyones happy (apart from the publishers).