Most Helpful Guy
I like how you're speaking about it from this perspective of "oh those other people over there with their strange ways" even though being straight is the default, you're in a minority and you've been bombarded by the idea of straightness since you were a child (including your own parents).
Anyway, from a subjective standpoint for the purely physical, there's just obviously something very attractive about the sharpness of a good looking male's features, the good jawline, the protective appearance of a taller man and the symmetrical aesthetics of a man with a well-worked on body. The rest is a little more unisex (such as eye colour, hair colour, nose, hair in general, etc). Pic related is a pretty good example of an "attractive" male.
I don't think anyone would dispute his physical attractiveness, even if he doesn't necessarily possess traits that one person is into.
From a psychological standpoint a lot of women just like that masculine, domineering presence I think certain men bring. Hell, even I get it as as a straight man, if a man who's older than myself looks and acts a certain way it can actually remind me of my own father (which is a positive thing). It's a presence of "yeah, this guy could take good care of me and I want him all to myself."
Frankly, I'm not sure why you would say you say you don't understand why it'd be attractive, surely you don't have to be a lesbian to understand the appeal of protective, caring masculinity? In fact now that I think about it I've MET gay women who understand why someone would be attracted to a man, so I just think you've got personal issues understanding this.1THIS IS NOT RELEVANT ANYMORE