Apple are reusing the older chassis to maximise profit margins. The SE was always a case of 'how can we still use this production line for another 3 years'. The current line is awful because of the terrible battery life.

The XR however was a lovely phone. Shove the latest camera and processor in that and you've got a winner.

It would be nice for the smaller chassis to make a comeback but if Apple can't make it work, nobody can. People want above all a good battery and those smaller phones just don't cut it.