Most Helpful Girl
Supply and demand- there are more clothing styles for women than men because women will buy them and men won't.
Compare a man's closet with a woman's. She'll have more clothes, because she purchases more clothes, consequently retailers will supply more female clothing because they know it'll be bought. If there was a giant increase in the variety of male clothing, men wouldn't respond by shopping more- retailers would just have to sell more of their leftovers to TJ Max. :)
To state the obvious, women and men have different roles in society- women tend to seek beauty whereas men tend to seek power. Also, interestingly, women are most attracted to powerful men, whereas men are most attracted to beautiful women. That's why you see rich/power men with supermodels. So, in short, supply and demand combined with societal roles would be my guess.