I think I would agree with you if my car had dedicated physical controls/displays for certain functions like climate and EV charging (dedicated/physical would be most ideal). But because everything is done through the infotainment screen, I find it cumbersome switching between CarPlay and OEM software, so I would like to stay in CarPlay and do everything through it, especially because the OEM software is bad.I don't see the point of Carplay Ultra. Are people asking for this? For me Carplay is enough music, podcasts, maps and phone is really all I need. The car can control the rest.
But one of the reasons it's cumbersome switching is that it takes a few button taps to navigate back to CarPlay depending where I am in the OEM software. This is also dangerous when driving and just bad design from the OEM. So if there was just a dedicated button (preferably physical) to immediately enter CarPlay, and if the OEM software was improved, then that might be enough for me.
Also one thing about wireless CarPlay that drives me crazy is the input lag. If Ultra somehow solved that then I would get on board just for that.