Eh? What makes you think they won't simply make patches available through the normal channels? And Valve aren't some evil corporation, they aren't going to charge you for patches or user-created content...
If anyone is wondering, head on down to city-17.net, and take a look at their list of mods. You won't have to pay to play any of those, and there are well over a dozen of them. I'm looking forward to Over The Top and The Last Great War particularly.
I'm going to buy the retail version of HL2, (with ML+ Mods, obviously) but I don't see why people are angry at Steam...
In addition to this, I think the fact that Valve is selling multiple types of HL2 is a good idea. Some people may not have fast internet connections, so Multiplayer or...