Different products for different peoples/usage.

If Bose made a refresh of the old wired QC25 I would probably buy it instantly just to be sure to have something when my current pair fail.

And having a removable battery ensure that the part which age the fastest can be changed trivially.

I've been buying used QC25s, there are plenty of parts available to refresh and keep them working. I think everything in them is off patent now so theoretically someone could start making compatible main boards and then the user base would be able to fully decouple from Bose's product roadmap.

the part I don't understand is why so few companies make headphones that are anywhere near as comfortable.

Why would you optimize for quick changing something that needs to be changed, pessimistically, every 2 years? You can swap the batteries in the newer models, it’s not that hard. In every other way the newer models are superior. Far better ANC, better sounding, better battery life, able to actually be charged… etc

Sony's WX-asdf-whatever-3 have pretty easy to change battery (I did have to replace charge port tho) and wired option.

Why the QC25s over the QC35s?