The only time I'd play a multiplayer RTS is with friends, I've never been big on the computer assigned stranger thing, and most of the time that would be with my flatmate. No seedy LAN party, just a bored tuesday night with time to kill at home.
Other times, if there were a group of us, we'd head out to an internet cafe with a gaming setup and play together in the same room so we can talk.
I really don't think the advent of broadband changed everyone's gaming habits. and just how fast your broadband is, depends greatly on what country you live in.