I wasn't really a fan of them in PSO2, they didn't really contribute enough to your overall experience. You could send them out hunting for materials, but you would come across those materials naturally just playing the game and at much quicker rate, but in NGS, I think they would be much more beneficial.
Hunting for materials in this game is clearly frustrating a lot of players. Having an Aux Partner in this game could take the stress out of it so easily. Being able to send them out searching for materials in a certain area while we focus on other tasks would be perfect. Leveling them up like we did in PSO2 would be a good way to improve their success rate.