I haven't touched EX primals. I haven't even tried Ultima. People say it's about on par with Titan HM and that's just not for me. I probably could do them, if I tried, but I don't want to. It's not fun, it's just work memorizing the dance you have to do and then executing it flawlessly for 7 minutes or whatever.
I kinda like CT because people can screw up and the run keeps going. Hell, an entire party can go down to Thanatos and you can still pull out a win. And I typically don't have to worry about getting yelled at or kicked in CT. Maybe occasionally one or two people will get pissed, but not as frequently or angrily as in the primal runs I've done.
So, no, I don't want more difficult content. Maybe if they change the game so that difficult doesn't just mean unforgiving, but I'm not even sure what that would be.