I will go ahead and try and explain what I want to do in more detail. It, in effect, will provide a very simple 'dumbed-down' instrument that anyone can play. It will be mind-blowing. Apple could already easily implement this, based on what I have seen so far. They will probably do so in the future (and try to make money off of it), or they realize that it will be too easy for people to play music, and it will in effect, kill the desire of the next generation wanting to tweak and fumble through their complicated software, and so they will hesitate to release it.
Possibly you have tried the Touch Instruments Chord Strips on the iPad, to understand what I'm referring to.
When I first experienced these chord strips, it was shocking. I now possessed in my hands the ability to 'play' a 'piano' in a manner that sounded like what would have previously taken hundreds to thousands of hours of training skill. It didn't sound 'mechanized'. When listened through headphones (or decent PA speaker amplification) it sounds like someone actually playing the piano. And it came for practically 'free' in GarageBand for IOS.
However, in trying to use this as an instrument in a Live setting, one immediately runs into a problem. There are only eight chord strips, pertaining to the song's Key signature, available at any one time. Most songs use more than eight chords, when all the variations of a particular chord (e.g., Gmaj, Gmaj7, Gsus2, etc.) are included. The chord strips can be customized. But that takes too long to carry-out while playing Live.
It seems simple enough for Apple to implement the means by which these chord strips could change, on-the-fly, based upon an 'instruction' given to the program. Now if the software could change these chord strips on-the-fly with a human instruction (pushing a button), then they should also be able to change on-the-fly per reading a chord progression 'notation' previously embedded in the song.
If that is possible, then the next step, would follow: if the chord strips can change on-the-fly, automatically, then why would we need more than one chord-strip, and why should the human have to worry about making sure he is playing the right strip? Just display only one chord strip, which the human plays over and over. The midi notes being played by that chord strip would change automatically (be transposed, if you will) to the proper chord notes corresponding to the particular chord the song is calling out for at the position in the song. Voila!: the every-man's, dumbed-downed instrument that, nonetheless, sounds like someone is playing in perfect tune, complicated multi note chords, with chord inversions chosen at will (just like on the current chord strips), with articulation (as touch velocity is already interpreted on the current touch chord strips) without note errancy!