Well let's see, many of the audience didn't like Harry, didn't like Neelix, didn't like Kes, didn't like Chakotay. Were on the fence about Tuvok and Paris.
Nobody hardly talks about Torres.
So who did the writers real have left to write about that the audience did like?
So yeah, Seven had to make up where everyone else fell short.
Plus, when you do a marketing campagine that puts her image everywhere to get an audience to tune in, then as a studio you wanna try and get your money back. That means giving folk what they tuned in for. Her.
As Robert Picardo said: "If putting her image everywhere helps me keep a job, then I'm all for it!"