Bathrooms in flats are different from bathrooms in corridors, from my experience.
Bathrooms in flats are like home bathrooms, whereas bathrooms in corridors are more open, with multiple sinks etc - you're never going to be in a position where you can't get to one.
At Badock you pay £65 extra a year to have a sink in your room. Worth it? I'm not sure - you get less storage space, and I'd have nowhere to put my TV if I had a sink...