This is straight up not true. While it is true more boys than girls play videogames it's actually only a small majority according to some polls. Others seem to imply more women play videogames actually.
Nintendo has always pussy footed around the idea of Link being a real character or an avatar and it's clear they don't want to commit to the established character idea entirely.
Personal mods like this are perfectly fine. It makes the experience a little more "personal" tho certainly could be...