I used to work for Nokia back when they still made phones. Replaceable batteries were very normal then. Phones were a bit thicker than today but not massively so. These days phones are actually thinner but much larger. I had a "are you happy to see me or is that a Nokia" type Nokia 9300. That was a brick. But it had a full hw keyboard. and flipped open it wasn't that much bigger than a modern smart phone.
You could argue that the trend towards more energy dense batteries and wireless charging could enable new interesting form factors. Recent phones have magnetic connectors for external wireless chargers/batteries that snap to the back. Most of bulk and weight of a phone is for accommodating batteries. You could make an argument that making a phone with replaceable batteries is easier than ever. Many cameras have a bulge for the camera. The negative space of the rest of the phone could easily hold a swappable battery. How critical are those 3mm really?
If you filled the negative space on an iPhone 17 Pro/Max it would be a horrendously unwieldy phone. People who say this stuff seriously underestimate the disastrous effect on ergonomics increasing the whole phone from 8.75mm to 13.2mm would have.
I suspect (but am no expert) that the main arguments for integrated batteries are actually to extend the lifetime and sturdiness; drop your Nokia and there's a chance the battery pops out and gets damaged, drop it in the water and the battery compartiment is a point of ingress.
I'm arguing that the sealed / glued / tightly packed / irreplaceable battery thing helps keep phones working for longer.
Of course the counterpoint is that often the battery is the first component to go, and this law is intended to make it easier to keep them in working order for longer.
If you remember Nokia's batteries they were covered in a relatively thick ABS shell. They were also, compared to today, had laughably little storage. A Series 40 Nokia just did not draw that much power. The single GSM/PCS radio also sipped power.
Even if you stripped a 5G phone down to a Series 40-esque interface the 5G radios alone would use more power than a whole 3310.
In order to get the power density modern phones need they require high power Li-poly batteries. An extra 3mm worth of ABS shell is a lot of lost capacity. You can't sell user serviceable Li-poly batteries without a protective shell. You'd never get a UL rating because Li-polys are dangerous if mishandled.
The N95 had something like 995 mAh. A modern iphone would have about 4x that.
Also interesting to know is that BYD was supplying a lot of phone batteries back then. I think they also supplied to Nokia. Phone batteries is what made them big.
I have my 9300 still in a drawer ( checked ) . Interesting if it is possible to find a replacement battery for it and what functionality would still be usable? A physical SIM, 3G still works…
That's technically HMD a separate company but with some Nokia people involved. Nokia just licensed the Nokia brand to them and I think that deal ran out some time ago. I had a Nokia Android phone before I got my Pixel 6 a few years ago. Decent value device but the camera was a bit meh.
Nokia actually did an Android phone just before MS acquired them which they then promptly killed. And then of course they pulled the plug on the whole business unit. HMD apparently still makes feature phones based on Series 30. That's the pre-smart phone platform that a lot of Nokia fans remember fondly. The famously indestructible phones.
You could argue that the trend towards more energy dense batteries and wireless charging could enable new interesting form factors. Recent phones have magnetic connectors for external wireless chargers/batteries that snap to the back. Most of bulk and weight of a phone is for accommodating batteries. You could make an argument that making a phone with replaceable batteries is easier than ever. Many cameras have a bulge for the camera. The negative space of the rest of the phone could easily hold a swappable battery. How critical are those 3mm really?