There's also the matter of lawsuits. If you get a device, they're not supporting updates, so you go get a 3rd party update and it ruins the device, the RMA costs the manufacture, but worse, the customer(s) may file a (class action) lawsuit against the company over the problem of being unable to find the official firmware/driver updates, causing people to ruin their hardware, get RMA rejections, or not even being aware of an RMA process and simply buying another one.
Personally, I'd rather there be open source drivers/firmware for everything from day one, but to look at both sides, I fully understand the liability and why that's something that only exists in the hobbiest world.