Would it ruin a camera manufacturer’s business to document the camera’s hardware interfaces and operating system? Hardly. I suppose the documentation exists anyway. Otherwise they wouldn’t be able to program those devices themselves.
Opening up the docs would not make it less attractive to upgrade cameras. The main attraction of a camera is not its software, it is the hardware. We’re talking about the sensor here, the image stabilization, the many buttons and their clever placement, the tactile experience of pressing them, and so on and so on. Software just makes such a camera more usable for individual photographers.
Can you imagine being able to program any button for any function you like? You can do a lot of that on Olympus cameras, and in fact Olympus is frequently scolded for the “complexity” of their user interface. Most of that is just the configurability that we always ask for. It’s not even badly implemented, it’s just a lot of things that can overwhelm you.
But still, there are functions that can’t be bound to arbitrary buttons. Selecting aspect ratio is such a function. On the Panasonic LX5 I had it on a dedicated slider above the lens. That was paradise. I could change it blindly. On Olympus cameras the function is only available through some “Multi-function” button. You can bind “Multi-function” to any button you like, but you can’t unbundle the various functions bundled to “Multi-function”.
“Multi-function” is modal. Press it short, and you get the currently selected function. Press it long, and you get a menu to switch between functions. It’s not unusable, but it is still so far from being able to become automatic by sinking into muscle memory, that I rarely ever change the button from “Aspect ratio” to anything else.
That’s stupid, but it’s the way it has worked from at least the PEN E-P2, my first Olympus camera. I can live with it, but if I were able to change it, I certainly would.