A screw-on panel sounds like a good idea to me – a decent balance between replaceability and durability, without overly optimizing for a repair that only happens once or twice in a handset's lifetime.
The S5 looked a lot like my first smartphone, and it goes to the other extreme: a flimsy plastic shell over some sturdier plastic that frames the battery and separates its contacts from the phone's internals. My newer, non-user-replaceable-battery handsets – both Apple and Android – have held together a lot better using fewer materials more judiciously.
A sweet spot between these extremes ("you need 80 lbs of specialized equipment to replace the battery safely" vs. "let's pretend people need to swap out phone batteries like AAs") could be good for me, but I want to know about the trade-offs. Too often legislators and right-to-repair advocates talk as though there are none. Even with a screw-on panel, I'm sure there are trade-offs.