Leaving aside the separate channel of amplification and EQ for each pickup, I have left/right stereo questions.
Is the desire to create a left/right spacial separation in a live audio image?
Since ordinary acoustic instruments like the trumpet, sax, piano, upright bass, guitar, drums, etc., are essentially "mono," is there a musical advantage "stereo" provides the electric bass that the others already have?
Or perhaps, is it to create something interesting that has no analog in ordinary instruments?
I am having trouble with the idea, because it seems to me that with FOH/subs, monitors, side-fills, and on stage amps, there are already multiple sources that each likely have different EQ profiles, none fo which make for a deeper or richer audio experience, over the sound of an un amplified live acoustic ensemble like a chorus, orchestra, or Jazz band, chamber ensemble, IMHO.
In fact, generally I find live amplified music to be "flat" (boringly the same all the time) in terms of the "sound stage," once the modern FOH people have their way with us.