I appreciate finding the positive perspective on this. I agree that a replaceable battery is a nice plus, and I suspect that almost everyone would agree that by itself, a replaceable battery is better than a non-replaceable battery. So why do you think companies don't do this? After all they want to win customers, so why not just build it this way in the first place? Because there are adverse effects to some combination of size, weight, cost, and time to develop/iterate, which customers care about even more.
If enough customers really cared about this or ANY feature within reasonable engineering reach of manufacturers, they would already offer it. In fact, it was fairly recent history when many cell phones still offered replaceable batteries. Further back, I used to buy a few spares and a separate charger for my old Samsung Palm Smartphones back around 2002-2005 so I could have more power with me when I traveled for work. When one ran out, I'd just slap in the replacement.
The reality is that CUSTOMERS told companies that thin and light were more important than a replaceable battery in certain classes of devices. Obviously, not every customer agreed with that prioritization, but that's where competition would step in to fill the gap, if there really were a market interest for this. Given that some manufactures kept offering replaceable batteries for quite a while, we can see that they did more than try. They even pushed these, promoting replaceable batteries as a critical benefit. Customers en masse said with their purchasing "we don't care about that enough to sacrifice thin and light."
This is the PERFECT EXAMPLE of excessive government regulation harming customers (most regulations do). Some bureaucrat has data, or a personal bug up his/her butt, that users would like replaceable batteries. True. He or she then pushes for a regulation to require it with no comprehension of the market impacts of this change.
There will surely be plenty of ignorant people praising this, because again, who wouldn't want the ability to replace the battery? But they completely miss the history and the long-term unintended consequences to this. Worse, because it's also expensive to produce fundamentally different models for different parts of the world, this means we're probably all going to suffer the consequences.
Good for you EU, you've just made all electronic devices worse and more expensive, as proven by customer purchases over the past two decades.