interesting question!! yes, you never have a thought about someone's ears...

it must be that the view of someone's genitals trigger something in our heads! in the sex- or lust-centre. being attracted has a function: sex ===> reproduction.

also, i think there is NO part of the male anatomy that differs in size randomly as much as the size of a cock does! BIG guys with tiny cocks, small guys with HUGE cocks, ALL is possible! and that's intriguing..!

That's the most interesting part about sex,...it can't usually be intellectualised or analysed,....you just have the feelings and desires that you do. Yes, the penis is quite an uninspiring pody part most of the time and when one sees a group of men naked together they can often look quite comical as their genital swing about between their thighs,....but photos on the web make me think that as men get erect the whole look and atmosphere changes to a more meaningful air...