Well, the OPs question is one I have pondered. I don't love all basses but for no other brand have I picked-up and consistently thought "***????".
It is not from a lack of trying. I was at a rehearsal studio recently and excitedly asked to test a Gibson bass they had; I tested it, then excitedly put it down and picked up my Ric.
The same scenario at a shop with regard to TBs of both the Gibson and Epiphone variety, plus EB'ish basses.
I can appreciate most basses (even if I don't actually like them) though Gibsons nearly always escape me - I am lucky I guess because they are not cheap.