Regarding clip-on back vs using screws: I prefer a clip-on back, but using screws is still acceptable to me. I really just don’t want it glued shut. And as long as it still has a MicroSD card reader and sim tray accessible, that’s fine.
Regarding the use of USB 2.0 rather than USB 3.x: I disagree with this design decision, but I also can live with USB 2.0. I would mainly just use it to copy files, and this just means that doing so will be slower.
Regarding the absence of desktop mode: This is not a feature I use, so it doesn’t really change anything for me, as long as Android Auto can still work via Bluetooth.
Better CPU, better screen, those are standard upgrades whenever a new phone is released, and to be expected. I think the CPUs generally are fast enough.
Camera: I don’t really pay much attention to smartphone cameras. If I want a high quality picture, I take out my Canon R5. If I just need to record some information, I might use my smartphone to take a picture of it.
No headphone jack: This is my biggest gripe and the reason why I won’t buy one.
Mind you, if I was considering buying one, and I was one of those people who for some weird reason didn’t care about the headphone jack, it would be competing with the FP5 for my money. And the FP5 does have some advantages over the FP6.