There is a little ritual we do here from time to time where someone writes a comment that starts something like "Well, I didn't expect Stallman would be right about [issue now being reported on] but he predicted this years ago".
If it can go wrong it will, and if software isn't free then its owners will do things that the users really do not like. In this case, if they can fix bugs they can reduce functionality post-hoc. That is consequential. It is better to have freedom or certainty as to what a device does.
How can you ever really be sure that there is no way to change the code running on the hardware, either unintentionally via some exploit, or intentionally via a deliberate backdoor or a debugging interface enabled in production?
As a practical example, I have never heard anyone considering the freedomness of firmware in eMMC flash memory chips. But the talk "eMMC hacking, or: how I fixed long-dead Galaxy S3 phones" from CCC reveals that actually, Samsung eMMC chips have an undocumented debug interface to read/write the RAM of the firmware running on the ARM core inside the eMMC chip.
If it can go wrong it will, and if software isn't free then its owners will do things that the users really do not like. In this case, if they can fix bugs they can reduce functionality post-hoc. That is consequential. It is better to have freedom or certainty as to what a device does.