The Suzuki Omnichord was introduced in 1981 and has been used by professional musicians and beginners alike. It has a touch plate and chord buttons, making it seem almost too easy to play. Beginners can play straight away, and pros can use them to work out new tunes whilst on the road.
The later versions (QChord) have midi interfaces and song cartridge capabilities. Used by people like Bjork, Bowie, Elvis Costello and even Dolly Parton. Oh my.