I think this is where opinions will vary wildly about who is a viable candidate for a Signature or Tribute model, based mainly on age of the person you ask.
Both the Allman Brothers and Grand Funk Railroad sold way more records than Thin Lizzy but their bass players were not the front man.
Jimi Hendrix or SRV guitars and Sting or Flea basses are no brainer choices.
The Dee Dee Ramone bass was limited to 1000 basses (I think) and the Ramones were culturally huge to a much bigger audience compared to Thin Lizzy.
This is where I guess Fender would go look at that Rolling Stone list of greatest (most popular in their eyes) bass players of all time thing.
What's strange to me is that Dee Dee Ramone, Paul Simonon, Sid Vicious, Phil Lynott and a ton of other famous bass players played stock Fender Precision or Jazz basses.
So, I see no need to buy their Tribute/Signature bass because a Dee Dee/Paul Simonon/Sid Vicious bass is just the punk standard white P Bass with black guard.
Where Sting has a bass you don't see every day, or Dusty Hill or Flea or the three guys I mentioned, all functionally different than standard Precision and Jazz, so for me maybe a reason to want one.
But the Artist Series instruments, and the Phil Lynott or Dee Dee Ramone limited run helps keep the Fender mystique going that they are the center of the guitar/bass universe past, present and future, which is a good thing for them.