I started asking the same questions as the OP way back in the AxeFx Ultra and early AxeFx II days. Though I still chime in on the topic, I've given up. Fractal Audio is all about quality in everything it does, whether it is bass or guitar amp modeling, or effects of any kind. I've always been a vocal supporter of FAS and will continue to be. It is fantastic gear PERIOD.
....and here's the BUT....
As a bassist exclusively, the number of additions targeted at bassists has always been a painfully slow drip. This is not the first thread of its kind, and many previous threads have included very specific requests. Generally speaking, those request threads atrophy and die on the vine.
Are there good reasons why there isn't a GK, SWR, MarkBass, Eden, Sunn Coliseum, Acoustic, Hartke, Aguilar, or Ashdown among the bass selections? I'm sure there are, and those reasons have all been mentioned in this thread. The best I can gather, though, comes down to a combination of lack of interest from FAS itself, reinforced by lack of resources, and lack of return on invested time.
I'm sure FAS has run the numbers and are comfortable with this reality, and honestly, I don't see where this has much - if any - impact on their target audience. But since there are other modeler companies that do take a more active interest, bassists do have the option of going elsewhere to have that itch scratched.
FAS continues to be THE preeminent name in digital modeling and effects for guitarists IMO. It also provides plenty of technical tools for bassists to custom craft their ideal bass tone provided time and tech savvy allows for it (I'm sure most bassists would prefer turn-key accurate amp models over home brew). The one thing that FAS products do not offer is a wide variety of Bass amp models. So if that's what you want, the history of FAS should tell you that you, the bassist, will be left to your own devices to somehow emulate your favorite (not modeled) bass amp.
I'd love for this not to be the case, and to be proven totally wrong. Still, if I could justify the cost, I'd jump on an FM9.