It's not the fact that there's a pocket door. That does provide plenty of privacy. But it would be awkward to be taking a shower in the room where my DD and their friends were hanging out. The sink/mirror area is all out in the open, and I'd be there putting on my makeup, doing my hair, etc. - - awkward/no privacy. Granted, it wouldn't happen often, but if they had a sleepover, and they were all sleeping late, it would be really inconvenient for me to take a shower, or even brush my teeth!
There is a half bath downstairs. But it's just a pedestal sink, not really room for "getting ready".