People are *supposed* to have fat there. It is where the lymph nodes are located, in the auxiliary fat pad: http://pie.med.utoronto.ca/ALND/ALND_content/axillaryAnatomy.html
If you didn't have fat there, you would have bigger problems than presumably-not-appealing-to-the-heterose
xual-male-gaze, like chronic swelling of the hands and arms. Which I'd presume is also not attractive?
The patriarchy needs to spend less time believing "women" are those computer-generated models in their video games and more time in an AP Bio class.