This happens with trams in the German city I live in. The other advantage is energy efficiency, apparently - if you can keep them traveling at a consistent speed, then they can maintain momentum, as opposed to if they're constantly stopping and starting and need to spend more energy getting up to speed.

It's slightly irritating as a pedestrian when you're waiting to cross the road to get to a tram stop, and you see that the tram is coming in less than a minute, and you know you're not going to be able to cross in time. But that's the sort of slight irritation I'm okay with for better fuel efficiency and faster trams.