Pages Feature Request: Create Mailing Labels from a Numbers file

I create a form letter in Pages using data from a Numbers spreadsheet. I print the letters. Done. Beautiful and simple.

To mail the letters, I need mailing labels. I export the Numbers file to xls format and transfer it to my wife's computer (she's a Microsoft user.) Now I use Word with the Excel file to create my mailing labels.

Can't we please have this useful feature on the Apple side of the fence? The "Contacts" workaround seems even kludgier than what I'm doing with Word and Excel.