Each Gen after 7 should have only gotten 2 or 3 Legendaries and then 5 or 6 Ultra Beasts. It would allow Game Freak to add a shit ton of Legendaries like they usually do, but it would make actually Legendaries for the region feel more rare. Ultra Beasts are other worlders that don't belong in a specific region, so while they are functionally the same the distinction would help make Legendaries feel more special again.