steam has to get much better before its useble, hell even for HL2 it seems to be more of an obstacle than a usefull tool. its a good idea on paper, but it'll be awhile till all the problems with it are fixed and it works as intented.
self publishing is difficult nowadays, you still need money for development, the "we'll pay you if this sells" type of policy will not attract alot of developers, especially good ones. And the distributing takes alot of work, publishers take care of all that, but if you try to do it all yourself you'll find that you have to go through alot of **** just to put the game out there, even if the box is empty.
Internet is cool, you could distribute things on the internet, hell thats how id got where they are at, thats where steam comes in again as pretty much the ultimate distribution medium, its not perfect, but it kinda sorta works.
BUT you still have to make the game, which is pretty much your main battle, just to get it done, takes alot of effort to make a game. Development is the main problem not distribution, although thats difficult too, all in all there are alot of difficulties associated with making and distributing games, and it takes alot of people to get things done, and you need good capable people to guide the game every step of the way to make things work.