Women often desire tall men and a big penis, which is genetic and uncontrollable. While many would get upset at men for desiring a slim women, which is controllable.

EDIT: After seeing the rise in popularity and controversy of /r/fatpeoplehate, coupled with previous online dating experience, I thought about this. There's definitely a definitely a discussion here, which is why I posted it. I'm certainly not saying that all women desire one thing or any other generalisation. And if you think it's because I am short and have a small dick then let me assure you otherwise - it's like a Super Mario warp pipe.

EDIT 2: Breast size is a good counter argument too!

EDIT 3: See the response from /u/slothbuddy for an excellent counter-thought!