This is planned obsolescence at its worst, opening up firmware once you drop support for a product should be mandatory.
I would say what they are doing with Squeezebox is the best case scenario for a lot of these connected devices, even though the complexity of having a self-hosted option is in no doubt part of what lead to their failure.
The squeezebox ecosystem is my go-to example of how to do it correctly and build a product that respects the consumer.
The server is open source (just a bunch of perl) and freely distributed. It runs locally and the players don't need internet connectivity. It can never be obsoleted or killed because everything is local.
Sure, the company has long, long-since discontinued the product so they aren't developing updates. That's fair. But they also don't (and can't) do anything to disable existing functionality.
I have many squeezebox systems (including a transporter) scattered around the house and they work great, just as they did in 2003 when I bought the first one. More importantly, they will never stop working (other than hardware failure, but I have many spares).