There are bounty hunters and then there's the whole tragic story of the Fett's, as far as appearances go.
Apparently it wasn't recognized, right, how popular Boba Fett was, you know, in the 3 seconds he was a badass shutting down Luke or out tricking Han. Plus, you know, awesome on screen presence. And then his death ends up being stupid. We all sort of know what happens is, in the name of fandom, Lucas has a big old fight scene starship-wise and 3 more seconds of much better dying at the hands of the Jedi. But that's tampered with some **** silly scenes of kid Boba Fett and, well, a generally weak excuse that he was the model for all clones. Okay, whatever...
Then we have all this esoteric lore about making Mandalorians awesome, anti-Jedi, etc. Follow that all the way up through Rebels, and Mandalorians are a thing, throughout.
The question is, do people want to see bounty hunters? Or do they really want more Mandalorians? I'm not even saying whether it'd be a good idea or bad to include Mandalorians, but I have a feeling most people are wanting that than strange lizard headed or even weirder droid bounty hunters.