Yes, you're right, of course you can export birthdays as a vcard if the app support birthday field. I wrote 'import' and I mean the default contact application.

is a joke.
You have all your contacts in GPE Contacts. And then?? You can't tap to the email address to start the mail app. You can't tap to the phone number to dial the phone number of your contact. GPE Contacts is useless now. You even can't mark the text and copy/paste into anything.
Yes, I could edit my contact in GPE Contacts and then copy/paste a mail address. But sorry, I'll do this never ever. This behaviour from GPE contacts is everything but not productive.