On Voyager alone, you had Wang, Beltran and Mulgrew who had some questionable behavior.Feeling but especially behaviour, which was totally unprofessional.
It seems to me that today, studios are much less lax when an actor/actress give trouble and don't hesitate to get rid of the most problematic of them (well, except CBS which keeps actors accused of inappropriate behaviour and gets rid of women with no reason except the famous "it was an artistic decision), even if it implies the end of a show.