I believe the trend is more about people using their phones as their main computing device so a bigger screen is desirable to many. I'm still on the original iPhone SE but the battery is definitely on it's last legs.
It only costs about $50 USD for a battery replacement from an authorized Apple service provider. If you're satisfied with the device otherwise, a new battery will keep it going for far cheaper than a new device.
FWIW, I just got an original SE new in the box for around $130 a few months ago after my last one went for a swim, and it came with 96% of the original battery capacity as reported by iOS.
My goal was for it to just last me until the 12 came out, but I'm still on the fence about whether the better camera (and water resistance...) are worth the additional bulk.
I used an original SE until my current XS. I didn’t want a larger screen, necessarily, but UIs started making buttons smaller and it became harder and harder to use. My Airpods also work better with the XS, and I assume it is because the smaller size has antenna limitations (although I know nothing about the subject).
