Just wondering, is this "trend" you're talking about just the Bambulab situation, or are other manufacturers doing the same? I'm not super up to date on 3d printing news, so not sure if i missed more such changes.
If it's the bambulab situation, it's not entirely unexpected. When they started people were already worried about exactly this seeing how closed their ecosystem is. Then again, they did make a printer that just works better than the competition, and that's in the end what attracts users.
Personally i have diy 3d printers that i built myself, really happy with them, but for people who just want to print things, many other filament printers are just too annoying to work with. Not everyone is into diy, and many people just want to make cool stuff and not care about the printer, and bambulab really made the next step towards achieving that.
So if the open source community wants to compete with that, they must make printers that are as user friendly. My diy 3d printers are like running linux. Really great and customizable if you like to work on 3d printers, and really reliable now i as an expert built & tuned them. But most people just want to buy a machine that works, and that's not these open source printers. And as long as we just focus on making 3d printers for expert diy'ers, we'll end up in the same place as linux is for OS'es: used by experts and for specific advanced usecases, but beyond reach for the common user that's then stuck on systems like apple/windows that are more locked down, but actually just work without having to understand how the entire thing works.