button orientation does not the sexual orientation of a shirt make. Its still a mans shirt because thats what it was designed to be.
As for conventional button orientation. The chessed over din thing is the reason for the chassidish deviation from the norm. Buttons, funny as it may sound are actually designed for to be easier for right handed people, we use our right hands to do the pushing of the button through the hole which is merely held by the weaker left – true story.
The female deviation from the norm originates with 19th century Victorian women. Women, who would be dressed by a servant, wouldnt fasten their own buttons. The button orientation was switched to accomodate the right handed servants who would now be able to mimic the motion on their own clothes, on the womens clothes.