I've been running these for 5 seasons. They hold the grease in and help maintain a waterfree environment. Like you, I have bearing buddies. I'm told that overenthusiastic greasing of the bearing buddies causes the seals to pop out. I've curbed my enthusiasm on the gun and have reduced seal replacement frequency. FWIW, I'm on my original races (removed and inspected annually) so there's a saving to be made.
EDIT - without the seal, you will have excess grease spatter all over the wheel rim. If it gets to your brakes.....