without all the extra parts needed to support these features you can make the phone thinner
The Galaxy S4 from 2013 has a removable battery, headphone jack, and sd card slot. Its no thicker then a modern smartphone.
cheaper to make
I’d rather pay more for something that lasts me longer. If users can replace their own batteries easily and expand their storage, they can hold on to the device for longer. That way they’ll buy less phones and won’t care that the product was minorly more expensive.
Bluetooth headphones have become very common
And have flooded landfills with batteries. Wired headphones don’t have batteries that will degrade or need charging.
internal storages have become large enough
Not really. I have a 64gb phone and need an sd card to store my music. If I wanted more storage I would literally have to buy a different device. I’d rather just have an sd card slot.
people buy a new phone often enough nowadays that battery wear is not as much of an issue
battery wear is part of the reason people trash their otherwise working phones. People buying phones more often is a symptom of not having right to repair.