We did a lot of 400 hz in computer rooms and that comes with it's own problems. To start with you really start needing very finely stranded wire because the current is starting to be a skin thing and not flowing through the center of the conductor. The main advantage is smaller transformers. I suppose motors could be smaller too because they used 400 hz for naval servo systems and that was the main reason there.
Why North America chose 60hz and Europe chose 50, I can't answer but the center tapped single phase (120/240) was seen as a safety thing when Westinghouse and Edison were fighting over AC v DC. In those days it was really more like 110/220. These days most motor driven stuff really struggles at 110 v and likes 120 a whole lot better..
