Sexualized animal pictures is, to me, completely bizarre and borderline deviant. If you're into that, fine, but it's not exactly normal to find other animals arousing just because you throw a pair of breats on them. And, no, comparing it to a Twi'lek or a Klingon doesn't standup. For one thing, Klingons and Twi'leks are not real AND they're played by regular ol' human beings. You're objectifying animals and making them into sex objects.
I get where you're coming from–sort of–but I think you're underestimating the amount of human in the average furry character. It's a lot more than "sticking boobs on an animal" and calling it good. Furry characters (the sexy ones, at least) obey almost all the rules of drawing a realistic human character: the breakdown of the body, limb and head proportions is human and the structure of the hips, shoulder girdle, neck, (often) eyes, upper legs and arms is human. They have a lot more in common, conceptually, with Klingons and Twi'leks than you're admitting, being essentially human frames augmented with spots, hair, flaps, fold, scaled, ridges funny ears or all of the above.
It is, deviant, though, socially. As to whether it's psychologically disturbed...well, my therapist seems to think I'm okay in this area. Pretty messed up in other
areas, but the furries seem to be okay.
Now, letme put it another way: WHY? Why would you want to make animals sexually charged? Is it some sort of artistic statment? What's the appeal if it's not sexual?
The non-sexual stuff appeals because it looks cool. I don't really know how to explain it, beyond this kind of art makes sense. Human-styled animals look "right," and have since I was a kid and spent hours reading Calvin and Hobbes
or watching Disney cartoons.
As for the sexiness, it's the same sort of thing. Tails and ears and big, limpid cartoon animal eyes are cute and cuddly, thanks to years of association. It makes more sense to me than having a thing for Klingons, precisely because animal characteristics actually exist and are more "real" than freaky fantasy beings that have no reference point to reality.