You might call this the Red Sonja Effect. Why did she always wear a tiny little bikini of armor? She was a warrior woman, and she should know that more armor is better in combat. Redheads are smarter, you know.
In World of Warcraft, as my female Night Elf Warrior leveled up, she would loot armor with better stats. And the armor always got smaller. Well, not always, but it wasn’t unusual for Item Level 49 to be a full chestplate of armor and Item Level 50 to suddenly become metal pasties.
As shown in the accompanying image, armor looks different on gals in the game than it does on guys. That’s the same armor, called Pants of the Naaru, shown on a female toon and a male toon. Smart clothes that change to fit your gender! This would cut the size of department stores in half.
This lovely article explores the issue with many more illustrations. It also links to another awesome article about drawing men and women for comics and how they’re different. You can say this is just pandering to the majority of your customers. You can say I’m part of the problem since I’m a guy who wanted to look at female elf butt for a thousand hours. You can say all of that stuff, and you’d be correct.