What you're describing, and I agree with you, is what many legal right to repair advocates are fighting for.
However you'll see many people conflate it with easy to repair and easy to get parts, or repair without voiding warranty. Which IMHO should be separate talking points, but alas, they're all jumbled up when these discussions happen.
It's also why I don't think right to repair will please most people. Because the scenarios you described are limited and outside what most people are thinking e.g home repairs of cell phones
NEC Medias smartphone from 2011, removable battery and IPX7 which is waterproof up to 1m deep. It is 8.2mm thick.
The Iphone 4S was released that year @ 9.3mm thick.
It is possible to make phones that do it, the companies don't want to.
Even given that, I don’t see how “end users must be able to change batteries in a practical way” would not negatively impact the quality of the iPhone I’m holding in my hand right now.
From a water-resistance standpoint alone, I think my phone would suffer in at least one dimension that matters to me. (It’s an Xs Max and yes, I bought used, confident that the water resistance was intact. If I sold it now, the next buyer has that same assurance.) Phones get wet at some low (but not insignificant) rate; it’s hard to avoid that across the entire population.