I may be in the minority, and I have not read this whole thread, but when it comes to signature basses, or any signature instruments for that matter, I feel that they are targeted towards two different groups: collectors and tribute bands. For the collectors, you have people that love a particular artist and/or band so much that they will buy the instrument simply to hang on the wall as part of their 'shrine' to that artist or band. The tribute band buyer concept speaks for itself I think.
Personally, there is only one artist bass I would want, and I would definitely fall into the collector category on that, which is why I have never bought it, and that's the Geddy Lee bass from Fender. Ultimately, I satisfied my desires from the collector standpoint with a bunch of Axe Heaven instruments.
I really believe that most vendors making signature instruments are marketing towards those two groups, at least primarily. A perfect example is the Mike Kerr signature bass from Fender. Talk about getting panned in the reviews! However, if you watch Mike's video that Fender released, he specifically addresses the gripe most people have with the bass: the bridge pickup. He says that it is primarily used to help with the 'guitar' sound when tracking in the studio (or something like that). Which brings up what the OP stated about a bass that was built around the ideas and needs of a specific player, and meshes with their style and whatever effects and amps they use to get their sound.
I personally think most of the signature basses are lame. They really aren't much more than lipstick on a stock model to mimic whatever changes the artist made to their bass for their own personal tastes and the company then slaps a decal of their signature on the instrument somewhere, jacks the price up by a few hundred more dollars and prays there are enough fans that want that model to justify the tooling and effort to make them in the factories. There are some that are released that I just can't wrap my head around at all, to be honest.
Again....just my opinion, and I'm sure I'm in the minority.
