Gentlemen, this is a great topic. As someone who has worked for both Elektron and Pioneer DJ, I can tell you that this kind of thing is very exciting, and the possibilities are so appealing and alluring, but the practicality is EXTREMELY low. I have suggested the same things and been equally as excited by the possibilities. I like your ideas about visual customization a lot, Harry.
I share your enthusiasm for this, I really do...but I gently request that you think about the implications of this before letting expectations run wild. Every change to the OS creates a new OS. Which one will be the official one? How many OS versions would a company be expected to support and troubleshoot for paying customers? The support resources alone would be immense. Even if that were managed somehow, the interconnectedness of the embedded code on standalone hardware music devices is intense--and so the ability to create problems in other areas of the OS by opening code to user changes, even small ones, is a pandoras box of very unhappy customers who expected something to work and then had their machine crash on stage at a paid gig. Pioneer DJ products need the stability to be relied on by industry professionals getting paid to keep a show going. Open source is not popular in the mainstream pro-level MI world yet for a reason. Korg has toyed with this with their xxxxlogue series, just with the effects engine...it seems to be working ok, so, there's hope on the horizon, but it's a very small chunk of code in a very confined space.