Have you seen/played Super Aces Bonus, Phil? No kickers required in that game, either, the Aces still pay 2000 and you get 3-for-1 on trips (instead of 2-for-1 on Ultra).
The main difference between the two is that quad 2s-4s pay 400 in Super Aces Bonus and 800 in Ultra Bonus, but again you get the full payout on 3OAKs in Super Aces.
Edited to add:
I just found this from about a year and a half ago playing Super Aces Bonus:

Not bad for holding one ace, huh? Worthless kicker, naturally.