I'm in too minds about this. Obviously I drive cars too and there's nothing more frustrating than being stuck behind some Lycra-clad asshole pedaling at 15km/h in the middle of the road as if they own it.
I think more could be done to promote good rider/driver etiquette.
At the same time, where the fuck are they supposed to ride the bike? And bikes are a better way of getting around short distances, around town etc.