Height

I think Husbands should be taller than wives. Because Husbands are meant to be the protector of the wife. I don't mean that a wife can't protect herself, but for a wife it is not required to fear from any problem because if there would be any problem, then definitely her husband will protect her. No need to depend on others. Also i think that the couple gives a good impression if neither of them are taller or shorter. It would more fine if both have same height and same personality. Then they can be said as a great couple.

maybe it's because men are usually taller than women

not always... but most of the time. I guess women are generally attracted to men taller than them. Likewise, men are usually intimidated by taller women as girlfriends.

I think men normally prefer to marry those who are shorter to them, it is like one of the criterias in marriage, though that is not always the case.. i have a friend who is shorter than his wife, and he is still trying loads of things to get taller..lol

not always taller but may be because the couple looks good this way...i have such couple in mu home with husband shorter than wife,,and each time people make fun of them..and used to give very odd sort of comments.