Women tended to be dressed by others
Women tended to suckle on the right breast and so found right-over-left buttons more convenient
Hmmm. I'm a little iffy on those women's closures explanations. Really, only the upper crust of society would have dressers. Mr. and Mrs. live-in-a-hovel couldn't afford that and would dress themselves. And there were a hell-of-a-lot more of them.
As to the breast feeding explanation...that was surely made up by men since when you breast-feed, you try to feed from both breast or you wind up lopsided and sore in the breast that you are not emptying (the milk keeps building up since you lactate on both sides).
