Not trying to be Mr. Unpopular here. I just wanna share a perspective from a manufacturer's standpoint. MI manufacturer’s (at least internally) consider themselves in the consumer product market. At least the bean counters do.
Obviously a manufacturer could do anything they want but everything has a cost. Cost affects sales and sales affects keeping retail prices down. Most products get a price fixed to them when they are designed. Replaceable batteries have a cost which means if they add that as a feature then something else will get left out. So decisions get made.
Pretty much everything I’ve seen runs over its cost estimates in its initial stages and things have to get cut back. Could be features, could be quality, could be making things serviceable. In older times a lot of gear was designed to do whatever the original design was damn the cost. That's not the case any more. Consumer products are designed form the ground up to meet magic price points ... $299, $399, $499, etc. While you guys certainly have the right to make decisions based on whatever you want I’m guessing in the bigger picture very few sales are lost because on non replaceable batteries assuming the original battery lasts a few years or longer. Apple products that sell in the millions are probably a good example of that. Even in house factory service bills $100/hr against a product in for warranty repair. So for about anything that sells for south of $500 it is cheaper for the factory to replace than to fix. Behringer fixes nothing these days. Warranty claims are replaced and everything else is non serviceable.
Once upon a time I climbed into a dumpster with about 400 rack mount Crest power amps that were on their way to be crushed. I could have easily taken parts from some and fixed others but that ain’t the way it’s done