It was Phil's express wish that his German family be present, their are descendants of his sisters.
I think the list is well in line with Phil's wishes, it's his immediate family (children, grandchildren and spouses), some Windsor cousins and his closest German relatives (from his sisters' children), so it's a fairly tight family funeral and family was more important than dynastic invitations.
The current (abolished) main line to the Greek throne aren't that close relatives of Phil, it's his uncle's descendants.
The Danes aren't that close relatives either, but the only still active ones, so they'll honour a prince of Denmark.