We've already got the system that makes it so our chocobo companion can be a substitute party member. We also have it set up where your egi's can be changed into carbuncles. Why not make another system where you can buy new models for your chocobo combat companion into other things? Easily you could have used various characters or even set it up where you can use your garrison members as your companion. It also opens up non-canon models to be sold on the mog station or crossover characters. There's a lot we can do here.