I can see you have edited the original post, so I decided to reply again.
Indirect is a keyword in what you have written. If you don't have a bridge, you can't really make adjustments for intonation and things... otherwise, you might have the strings going through the body without any bridge for "more sustain". You might as well build a bass out of a solid piece of granite, with carved bridge... but that's impractical. Hardware is only used to make adjustments to compensate for the strings.. If you could tune a bass or add tension without tuners, you'd remove those too, if sustain was that relevant to tone. Bridges and nuts having direct contact with the intended vibrating portion of the strings, dependent on the material used may have a dampening effect on the string, but it's the string that vibrates, and it's the string that interacts with the pickups to produce noise. The same is true for frets... without frets, the strings are dampened by the wood and your finger. The rest of the bass is irrelevant in the production of amplified sound. Yes, the resonance of the bass may counteract with the vibration of the strings, but this is minimal at best. In the grand scheme of things, this does not matter... you have ambient noise, microwaves, x-rays, radiation, and other things, all which are part of the environment, also interacting with your vibrating strings.
Scale length DEFINITELY DOES MATTER and I did not rule that out in the above posts. It matters just as much as having hardware to adjust and compensate for variation between strings. I feel that this is a strawman argument to attempt to invalidate the points I made.
When it comes to amplifying soundwaves, the only thing that is amplified is the vibration of the strings because they are metal. This disturbs the magnetic field produced by the pickup(s), and the disturbance is amplified and transduced into soundwaves. The resonance of the bass or the acoustic sound of the bass (and the wood it's made from) is largely irrelevant in terms of electric bass because it doesn't carry over to the amplified sound.