So you are saying that while you don't really like bodybuilders (overly muscular), a fit or toned body is attractive? (Just making sure I understand what you are saying)
it definitely is, especially so if it makes her stand out in the rendering, compared to other girls in the same game. again, have a run through Personal Trainer... the manager of the gym is runway material with large hooters, the japanese girl has a fairly toned physique, there's a chubby elderly, one that is definitely on the obese side, and more "run of the mill" standard hotties and even a few that I would not find attractive IRL, so every "shape" has a chance to shine, and in that game in particular, that makes the japanese girl and the gym manager stand out to me.
IRL, you could think of pro volleyball players, who tend to have great looks and a fairly athletic build, but being rather tall this athletic build is spread thin, so to speak, rather than bulky.
I've seen plenty pro crossfit athletes that I thought were too bulky and muscular, to the point of becoming masculine. did nothing for me, but they did have their own following of drooling guys..so it remains a very personal thing.
That said, if I were to pick between a hot volleyball player and, say.. Monica Bellucci or Jennifer Lawrence, the athlete would not be my first pick. But in a game with variety (which I always encourage and appreciate), there is definitely room for a more athletic build. Too many games have a selection of characters that vary solely in hairdo, skin colour/texture, or at best facial expression. So much can be obtained by adding a slightly more plump character, or one with, dare I say it stretch marks, or one with a larger (but credible) bootie/frame in the mix.
In the end, most of the appeal of the character, quality of the rendering aside, will be depending on context and dialogue anyway...