>optimizes the keys for either reachability

It doesn't because it only has a single row of keys. Piano music is full of awkward finger crossings that could be avoided with multiple rows of keys like on the Jankó keyboard.

>or feeling

You can texture or raise/lower the keys on any keyboard as you please. No layout has an advantage here.

>the range for one hand is smaller than the guitar's

True, but the traditional keyboard is even worse.

>there's no bending/sliding/vibrato

Exactly the same as a traditional keyboard.