I don't think your sex should dictate how you act or what you do. Rarity is a character, and an individual. Many of her friends are female, with different personalities and traits that differ from her own. She is not more or less female than any of the other female characters in the show. They should be seen for their individuality, not their sex.
If everyone were the same, it'd be boring. Women and men come in all sorts of shapes, sizes, strengths, weaknesses, qualities, traits, personalities and ambitions. Therefore I disagree with the "No man can" aspect of this topic. You could argue that no man can appreciate or should watch a show about ponies, yet they do, because individuality exists.