i think it is analigous to women's tits.
we like tits. we like big tits. but if they dont have big tits we are usually ok with that, but we would perfer big tits.
so if a women asks, "does tit size matter?" since we would be fine with normal size tits we would respond with this, " no, as long as i can grab them." but having bigger tits is better. so if we had the choice of the same chick to have a B cup or a C cup every guy would choose the C cup. And the same goes for women.
now some guys HAVE TO have a chick with big tits and the same goes for some women.
ta da! i solved the 'does size matter' question.