Manufacturers have tried breath controllers, ribbon controllers, footpedals, alternative keyboards and controllers, 'guitar strummers' for keyboards (anyone remember the Oberheim 'Strummer'?), wind controllers, etc....
And they failed! For an industry supposedly founded on innovation, musos can be a conservative lot.
You only have to look at some of the great synths that have failed to see how the vast majority of keys players want 'safe' - bread and butter piano, strings, basses, pads, organs, clavs, etc., not cutting edge, new sounds and ways of playing them and musical expression.
One of the most innovative technologies that has emerged, one that deviated completely from the subtractive, analogue paradigm was FM and one of the most successful synths of all time was the DX7. And what was it used for mostly? Bloody Rhodes, slap bass and tuned percussion! Why? Because that's what most people want(ed).
And hardly surprising... for all the talk of hi tech here and requests for new synthesis methods (or old analogue synthesis methods), etc., the vast majority of musos are playing covers in bands doing pubs, weddings, corporate events, parties, etc..
And it seems musos are a lazy lot as well and don't want to (won't) learn to play and acquire new techniques (many can't even be bothered to acquire basic technique!) so any instrument that requires a learning curve is likely destined for commercial failure.
Look at the Akai EWI. If you want an expressive instrument, look no further but it fell on its arse for the most part. Now, it was an ENORMOUS success in Japan - one of the first tracks featured on the then new Japanese MTV had a J band called 'T-Square', a jazz/rock instrumental fusion band with a Mr Ito as the font man playing EWI. The Japs went mad for it and something in their psyche had them sit down and learn to play it. Akai couldn't make enough of them. Schools opened up to teach it and sax teachers also started teaching EWI. I reckon at one point, you were probably never more than 10 yards from an accomplished EWI player in Tokyo!!
But Akai could barely give them away over here - it's like we've become so used to push button, instant satisfaction that sitting down for 6 months or more to learn an instrument is just not going to happen (and sax players for the most part are seemingly too traditional to adapt to it as well).
And manufacturers are well aware of all this - they're not going to throw pots of money into an innovative new technology if there's a risk it will flop as well it might if it veers too far away from 'the norm' ... so just give the punter more of everything in a safe package that will sell and keep the accountants happy (even if the superbly talented engineers in R+D are frustrated and hamstrung and screaming to create an interesting new product!).
But many of the decisions made in manufacturers' product planning departments are also largely influenced by their dealers, especially the large music store franchises in the US - if they don't/won't get behind a product and/or won't stock it, you're pretty much stuffed. These stores want to shift boxes which means safe products that won't tie up shop floor sales droids in lengthy sales pitches and demonstrations trying to explain new concepts. They want products that sell themselves basically!
But then there are trends so what do have? Loop machines for 'beatz' delivering four-on-the-floor dance and hip hop and ROMplers whose concepts haven't really evolved much since the M1 and D50, just more of the same effectively. They sell ... esoteric controllers don't. End of!
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