I think we may be underestimating our audience. Sure, they can't express the nuances of tone they way we do. We are very practiced at that. They are not. But that does not mean they can't hear it.
Sure, some in the audience listen to the individual instruments... sometimes even bass! That said, most compliments I get are about my playing. Every so often I get an unsolicited compliment from a non-bassist about my tone, however it often comes when I'm running DI into FOH, so my amp rig isn't even part of the equation. OK, my bass is still part of the equation, but I'm convinced that my choice of bass and strings simply wouldn't matter: P-bass with flats, Ken Smith with rounds, a good soundman will make it fit nicely into the mix.
I choose my instruments for tone, but that's for my own benefit. IMO, the primary importance of the instrument is not its tone, but that it's a "groove delivery system". Meaning: if my hands are comfortable on the instrument, and it works properly (of course), then its tone barely matters. The Warwick Thumb isn't my thing, tone-wise, but if I find it comfortable, then I'll make music with it to the best of my ability. If I play well, then the band won't care about its tone, the audience won't care, even I won't care (much!) I played a Modulus Quantum at some country/blues gigs, and the only thing my bandmates commented on was its appearance (specifically, the trans green quilt top). I just made sure its tone wasn't too bright for the oldies we were playing.
An amp rig has to meet certain requirements, the biggest being that it can deliver the appropriate volume without unwanted distortion. I'm aware of bassists who look down their snoot at low to mid range gear like Ampeg and Carvin, but I use that kind of backline every so often at multi-band gigs and open mics, and I've rarely encountered an inadequate rig. OK, so I like my own rig better than the Hartke 4x10 provided at last Sunday's rehearsal, but that's simply personal preference. I could have used that Hartke for all of my gigs (except maybe the stupid loud ones), and it would have been fine, nobody would have complained. And it was certainly a lot cheaper than my boutique gear. Point being: I spend $$$$ on gear because I want to, not because I need to, and as the OP says, that's true for most of us. Exceptions would be guys with special needs, like Jauqo and his infrasonic basses.