Valve is just getting people used to using it.
They'll fix the protocol problems and get powerfull enough servers eventually so that everybody can use it seemlessly.
What I figure is that Valve is using CS:S and HL2 fans as guinea pigs for a new business model based around digital rights management technology.
It's always been like this, most gamers don't give a crap about rights or anything like that, they just want convienence and good games and are willing to put up with a tremendious amount of crap in order to get it.
Case in point: places like Fileshack, Gamespy, and such. I hate it when I go to download a mod or something like that and all the mirrors are linked to places like that. I don't understand how poeple put up with crap like that... Ads up the wazoo, timed waits, horrificly difficult to navigate websites, pop-ups, broken links, weird subscription scemes. Everything that is wrong with the internet packed into a few "gaming" websites.
So Valve knows that you won't like it, they know that they will have screwed up servers time to time while they work out the bugs in there systems. And they also know that while people b1tch and moan, they will line up like good little boys and hand their money over for the "next big thing" just as long as they get the marketting right.
So you pay, they perfect the technology and when times come to use it to distribute things like subscription based movies rentals and other software over the internet they won't risk pissing off people that wouldn't put up with it. They'll sells services and software to other companies and that's probably were they are hoping to make most of the money from, even if future games tank. (which they won't)
At least that's what I figure. Probably wrong on a few counts, but so far it seems accurate.