Responsiveness = transient accuracy + dynamic range and a compressor, by definition, limits dynamic range. It is useful in that capacity, if you are into that sort of thing - you have every right not to be (I certainly don't want it all the time). The expansion on the bridge pup is genius IMHO even if, again, not something I want all the time (try it playing a chordy riff thru a OD/Distortion pedal, depending on the effect, as in how much it itself compresses, dialing in a bit of compressed neck into the mix for body/sustain can be nice). I suppose this may have been developed more with rhythm guitards in mind (we know that with Gibson, and most instrument makers, 6 bangers come first), but it works for me, and most other more shreddy bassists who tend to use these things as their main players. I know you complain about the sluggishness of the signal with the RD (e.g. poor transient response), but it's never been particularly so to me, though I tend to use it on things with longer notes vs fast runs so maybe, and I just don't care/notice it much.
To me, the hallmark of a cheap bass is clank, by which I mean being lean on the lower registers whether or not accompanied by excessive amounts of treble or mids. The RD is not lean in the lower register and not particularly middish.
On the other hand, the most sluggish (unresponsive) instrument ever, was one of the most expensive one of it's time (the Roland guitar synth (used for bass by the infamous Tony James while a member of Sigue Sigue Sputnik; I remember an interview where he said he had to learn to play a full 16th ahead; not sure if he was exaggerating, but it seems like it - anyway, that explains the lack of complexity in theitr basslines to a great degree).
and you editted and confirmmed my point:
But then I'm no fan of compression wherever it comes from. Takes all the fun out of bass playing for me.
Which is fair enough, but even you must acknowledge that many bass players love compression (some even too much). Recording engineers love to compress bass too; you'd be hard pressed to name a major label release with no bass compression from the last, say, 10 years.