Yes the return policy is so annoying. Here is what a hat owner explained to me though – when their policy was better, people would buy a hat, wear it that Shabbos and return it! How crazy! So his policy was no returns after Shabbos or a holiday (which made logical sense to me).
Also, I think it would be better if clothing stores at least had something similiar – at least give the person a week or so (unless they buy 2 days before Yom Tov) so that no one is wearing and returning.