skyko, though there aren't a ton of bassists using the AxeFx, over the last couple of years there have been regular posts that pop up where users request a few more flavors of bass amp models. To this point, there has been no action by FAS to indulge those wishes. I, along with others, agree that a few more bass amp models would be excellent. Personally, my take on the situation is that the AxeFx is a guitar toy, developed by those at Fractal Audio who are big fans of tube guitar amps and other guitar based stuff - as opposed to bass guitar. Maybe they care, and maybe they don't, but it seems to me that they would much rather spend their time and firmware updates addressing things other than bass guitar stuff.
All that said, the AxeFx is still a fine preamp/audio tool for creating tones for bass guitar. I have no qualms or regrets, nor any expectations that new bass models will be introduced any time soon or if at all. That's the way it goes. Perhaps sometime in the future, FAS will try to tap into the bass guitar market with some bass-centric features. I'm guessing that they may feel that, at this point, there isn't enough market share for it to be worth their while. And, many guitarists (and some bassists) are of the opinion that all of the tools needed to make great bass tones already exist in the AxeFx. In fact, I believe this is a true statement. This, IMO, should not diminish the value of having a few different bass amp flavors for bassists who would like less of a struggle and less tweaking in order to produce some specific, trademark bass sounds, which is already afforded guitarists with the numerous different amp types available.