As someone who uses USB rechargeable lights, the key point for me is USB, it makes everything so easy and flexible - I've got a couple of mains USB chargers in the house, I can plug it into my laptop at work, I can generally charge it up at someone's house if I'm visiting as it's a standard connection they're likely to have. By contrast, I had some of the lithium battery Chinese bike torches (can't remember the LED name but they were popular about 10 years back) and never quite trusted the charger, and it just seemed like a hassle as part of a regular commuting pattern. It could take 3xAAA instead (I think) but consensus at the time was performance would be noticeably affected.
In addition, between lights getting stolen and the last few AA rear lights I had falling apart on the bike over rough roads (the kind where the plastic front was removed to put in the batteries which seemed to cause a structural weakness) a couple of £4 rear USB strap-on lights is the best balance for my use. I have a much stronger Magic Shine on the front which is USB charged, but it's very compact and I doubt a similar sized light that took standard batteries would shine as bright or for as long, nor anywhere near. I once tested the battery life indoors, pointing it at a cardboard box so we didn't all get blinded, not realising that it was bright enough to singe the cardboard and probably set it alight if I'd left it much longer!
So the key point is replaceability - there's a drive for appliances to be home-repairable, so maybe manufacturers should be obliged to supply replacement battery units, but the cost would make it pretty much prohibitive, people would just buy a new unit, like they do with other electronics, shoes that never get repaired etc. Maybe there's a standard, large capacity rechargeable battery that could be used in such lights but still enable them to be plugged directly into a USB port, so you get the flexibility plus standard replaceability.
There's an environmental aspect to it, but if I put all the lights I've owned over the last 30 years in a pile together I could probably hold them all in one hand, and there are other choices we make that have more of an impact, so I'm okay with it.