Can you find the same exact light with wired in batteries and it's other version with replaceable batteries? I don't know of any, so I'd probably weigh my choice to other things about the light. Otherwise we get into manufacturing quality and design compromises.

All said, I've had my little daytime Bontrager Flares since about 2017. The internal re-chargeable battery still last longer than it takes to do a century ride. So what more do I need? More convenient for my use to simply plug in a USB cable than to have to remove them to charge. Though perhaps some have replaceable batteries that can be charged in place.