It is more style than architecture. Vaulted ceiling have been in style for a while and now it appears that crown molding is also in style "again".
Architecurially speaking, it may be necessary if you had a problem with the ceiling bowing and raising with the seasons. I also see it in movable manufactured housing to help cover defects from moving and settling.
Stylishly speaking, I see more and more of it on new housing but remember it will also tend to frame in your room so it "appears" smaller which is opposite of the wide open appearance you want with a vaulted ceiling.
Go around to some new housing developement, open houses, etc. and take a looksee. Good luck.