Ya, calendar is annoying. It's the only way to enter a "date" though.
You can alternatively use input masks though. Try something like 99/99/9999;_ in the body::esri:inputMask column for a text field... Or maybe even an integer field with the numbers appearance.
EDIT: Oh ya, just preemptively going to say that this is annoying for other reasons. You essentially have to enter in two digits for all months and days. Yes, there is an "optional" number option for input masks, but that doesn't alleviate the annoying method of input. Honestly, three separate fields is probably the most intuitive. Here, I put this together quickly: