I'd love a return to the old snap-fit plastic cases. Besides the ease of battery replacement, those phones seemed much more durable. Maybe because there was something that gave way on impact? I remember watching in horror as the plastic cover of an old LG shot under the display shelving at Home Depot at approximately the same speed the phone hit the concrete floor. I never used a case with one of those phones, nor did I ever crack a screen. It was tricky digging that cover out from under the shelving, however.
You can't have the thinnest/sleekest possible phone and an easily removable battery. Have to choose.
Frustrating thing is, mainstream phone manufacturers don't give you a choice. There's no option to buy e.g. an a slightly more ruggedized iPhone that is 15% bulkier but gives you easy battery access. That's a thing I'd buy, even if it cost a bit more.
The quest for "sleekness at all costs" made more sense 15-20 years ago, when full-spec smartphones and laptops were clunkier.
Hopefully the tide is turning. Apple is offering beefier and thicker laptops (M1/M2 Macbook Pros) and likewise now gives buyers an option for a beefier "Explorer Edition" watch. No battery access sadly. But hopefully the pendulum might swing the other way a little now.