I'm not sure that adding Jawa's "inflates the importance of Tatooine" ? They're just an iconic race of the genre. Given their culture, of being scavengers and traders, it seems just as reasonable that they would be migrating to other worlds, just like every other race. My enjoyment of the Jawa race doesn't really have any ties to Tatooine itself. To me, making Tatooine some super special nexus place in the lore, defeats the purpose of it being the "backwater hole in the wall" place to hide a kid with a mark on his head. But it is still a planet with a starport, and constant commercial traffic going in and out. No reason some Jawas wouldn't go off planet and join the larger community.
Jawas might be iconic but so are Tusken Raiders. And Ewoks and Talz.
I don't claim to know the rules that FFG uses when deciding which species is going to make the cut. However, I strongly suspect said species has to have a certain level of sociological and technological sophistication so that, in games, players are at parity with one another. While the isolationist Dressellians were barely industrialized when they first encountered the Empire, their active, organized opposition to Imperial rule forced them into interacting with the greater galactic community. Even in non-canon Legends material, the Jawas are just scurrying around in the background.