That is a good point, that just because Kes is more liked among the hardcore Trekkies who would watch the show anyway doesn't mean she was more interesting to the casual fans who might tune in or might not depending on the promo for that week.
But for a stretch in season three she seemed to have more stories revolved around her than anyone but Janeway or EMH. She just got less screen time because she was least likely to be put in a scene that had nothing to do with her because she was not Starfleet.
I think B'elana became far less interesting after about season two. I liked the way she was in Dreadnought but later seasons tended to focus a little more on her romance with Paris and a lot less on her technical genius or her anger issues.
Chakotay was considered a sex symbol?!