I have mixed feelings about that. On the one hand, I fully agree - I hate having all kinds of junky game clients running on my computer when I ought to just be able to have one, Steam, which is obviously doing a decent job.
On the other hand, I think that competition will drive Steam to be better (or maybe, just maybe, result in something better than Steam), and so I don't necessarily want the other companies to stop trying to compete entirely, either.