It's more of a desire for oils than a need. Humans don't need to eat processed oils at all. We can get all the essential fatty acids we need from regular food -- even without eating fish. Oils are not even healthy, they're just concentrated calories. It's just that they taste good.
As far as for other uses of vegetable oils, I can't really comment.
As far as for other uses of vegetable oils, I can't really comment.