Obviously it turns him on. He's not alone in that. A lot of guys like that. It's why they have women wearing high heels in porno movies. It just looks sexy. Trust. ';-)
Well heels are a great way for a women to show their legs and their nice behind. Maybe your man does not want you to express those good assets of yours to anyone but him self.
you probably look really sexy in heels and that is what turns him on. you might want to ask him what else turns him on so that you can do some things that turn him on before sex.
because wearing hills lifts your hind butt up. and he problably thinks that your are sexy when you wear them. So it turns him on. with out them, he may not get as turned on. but then if your sexy to him, then heals shouldn't matter any. Ask him.
mabey he has a foot fedish and does not yet know how to explaine it to you? or a possible a start to a fedish that he still dont know how you will react to when you know what it is.