If they plan to regularly rotate the games available on Game Pass Core it honestly seems like an incentive to just stay on that, or downgrade from Ultimate if you're only on console; if you're still paying for online I'd assume you must be using it regularly, in which case you're probably sinking most of your time into one or two online games at a time, so how many Game Pass games are you really finishing and how many did you truly want to play. At least with a smaller rotating list you'll have a clearer idea how many you want or need to play and the pricing is more sensible.
On the flip-side, how many people are paying for the game catalogue but obviously won't have the time to properly commit to any online game/service.
The whole value prospect of Ultimate is intended for Console+PC, so unless you're in that camp it'd be a good chance to consider what services are really necessary for you. Or you can just switch between GP Core and GP Console based on what you currently want to play.
If people just keep over-paying for services they don't use, it'll only make companies think they can keep getting away with offering worse value.
