>...Apple has a clear business interest in making it less easy for random people to enter that market.
I can see why Apple wants to do it, but wouldn't we think it wrong for Ford to seal their engine compartment with a security key that only Ford dealerships could open, preventing competing mechanics? Yes, in a frictionless economy consumers would factor this in to their purchase and not buy from Ford. But in the real world, this is a pretty easily correctable market failure (which can be traced back to the small number of competitors) which governments usually limit through competition laws.
This is a universally accepted practice in consumer electronics and not a universally accepted practice in automotives. Singling Apple out over it doesn't seem productive to me.