I think the battery system that’s best for everyone would be user-replaceable batteries. That way you can have an extra battery on hand to swap in as needed, or even extra-capacity batteries that make your phone a little thicker for people who are okay with that.

Those of us who do actually prefer thinner, lighter phones can still have them (maybe with a slight increase in thickness to accommodate the attachment mechanisms). Plus bigger batteries are a huge waste of resources if the capacity isn’t going to be used.