@Nyloth fetish's by nature have fan clubs so I don't know what your point is on that. What traits do you think a guy would want that Minthara has? A voice that sounds like 20 years of smoking with a dom attitude? Not even loyal in most cases. That's a specific fetish. Not trying to jump on you. This is just the blunt answer to save you some time and cut out the bs.
Personally I enjoy personality more than physicality, though if she looks rough I'll lose interest no question, in rpg's and Laezel and Minthara are not desirable. Shadowheart is just ok. Laezel at least has potential compared to Minthara, but I really doubt Larian will take her in the direction I'd like. I like Laezel to be part of the unification faction of gith or just a rebel against lich girl. Though for the latter, if ever, it would be an ending rather than a current state of being knowing Larian which would defeat the point for me. Larian is too big on dom and submissiveness so I don't even bother. I'm more of an assertive kind of guy.
The journey is the cake and the ending is the chery on top. I like journeys to be fun and not wait for an ending paragraph and picture saying "their better now, the end".
Oh and for sex scenes a fade to black is good enough for me. Maybe light scenes like DA Origins. More than that is not necessary for me personally.
But it is not specific, it is more a matter of taste. I mean, Lae's face is literally alien, and it can really be a kind of "fetish", but I won't say that about Minthara. Do you guys call a girl a "fetish" just because she has a rough voice? Rude.
Anyway, I'm sure Larian will still add interesting female companions.