> The microcontroller indirection is asking the vendor to put himself on the same level as their users. If the users cannot prepare updates, neither should the vendor. If the vendor can, so should the users.
How is-it "asking the vendor"?
If the vendor find an issue in their current firmware and release an upgrade, and the users cannot upgrade the firmware due to the "microcontroller indirection", the vendor will just say "you chose to remove the possibility to update the firmware, that's your problem now".
Note that for the firmware of a radio HW, this could even lead your products to be banned..