It (CC) does have a /models command, you can still decide to route everything to Opus if you just want to burn tokens I guess it's not default so most wouldn't, but still, people willing to go to a third party client are more likely that kind of power user anyway

They still have the total consumption under their control (*bar prompt caching and other specific optimizations) where in the past they even had different quotas per model, it shouldn't cost them more money, just be a worse/different service I guess