The issue here is exclusivity with the character's content. Her unpopularity in certain circles is a consequence of this, but shouldn't necessarily be the focus. Other characters in the TiTsverse don't get this kind of angst because even though some of them might be annoying obnoxious asshats (get your tight purple ass away from my ship's console, Sera), you can still do stuff with them or screw around with them regardless. With Riya, there is (in most cases) nothing. Their personality could be set to "Walk around and shit blue skies and rainbows", but it wouldn't matter. Most players aren't going to go through a full make-over just so they can make-out with one particular person, especially when there's so many alternatives. At a macrocosmic level, coming out with highly exclusive character content in this way, on a regular basis, would eventually become an issue too. Players would have to run around blowing fortunes in gene mods just get with a single character. It's more likely they would just get annoyed and avoid them.
Pretty much just creating a post to simultaneously pick up the discussion of this topic and not derail Franks thread even more. Don't have much energy atm, so for now I'll leave it to the new challenger and the old guard - who, from what I got, value the exclusivity as a way to allow for a more focused and refined content - to debate it out anon-to-anon.