[Art/graphics admin. modified due to size limitations in comments.]

Perhaps, since the Yetis were seen as an important element in the Nepalese traditional belief system, they (the Nepalese) felt the need to honor them by way of portraying them with a similar feature–although a natural one in their case.

Of course, I’m fully aware that this speculation can be reversed, and one could argue that it was the pointy skull of these creatures what inspired the people living in those areas to start wearing pointy hats in the first place.

Or maybe the Yetis come from France