The problem with HTML5 datepicker is that I can’t control the layout, so in fact from EME point of view it is just text, which is not usable to actually do something with (like check for birthday and send a mail).
If you don’t want to use the birthday field, just create your own custom HTML5 field and use that as birthday.
Hum … Interesting. Maybe I should make that a configuration option. For birthday it indeed seems more logic that way. But now your change affects other parts of EME where the calendar is used and the change needs to be kept after each EME update.
I’ll check the code some more.