Instead of new instruments, what about more options for existing ones?

[emekat]

If you want guitar, you already got plenty of options...
Acoustic, Electric, Acoustic-Electric, 6-string, 7-string, 12-string, 2-neck, 4-neck, Banjo, Classical, Resonator, Keytar, Tenor, Lap... Even Bass, as it falls in the same family
And let's not forget all the string types... Steel, Nylon, Nickel, Polymer....
(disclaimer: bass and ukulele are not guitars, but they belong to the guitar family.)

But only one guitar has controlled sustain.

I would love to be able to have two guitars one left and one right and with different EQing. Or two synths, or two organs, or multiple strings.