For most 3d games you spend 99% of the time looking at the backside of the character anyway. Lady butts are just better to look at generally.

Additionally in most character creation it seems easier to get a decent looking female character than a decent looking male character. I'm not entirely sure why but most male characters in games look like blocky fuzzy potatoes. When you start getting weird with fashion choices on top of that it just looks like a potato dressed like a goofball. With female characters you can go nuts with crazy hair colors, piercings, and wild fashion choices and it looks more deliberate somehow.