Why do we need to expand the palate?

[meltmylungs_]

I'm 17. Is this done purely for a smile? Or to widen byzygo? My maxilla is already a decent width (~14.5 cm), and the palate across the molars is 42 mm at worst. Do I need this and will it help move my maxilla forward? Because I'm recessed, haha (which is strange, because I've heard that a recessed jaw almost always comes with narrowness, and that's a zero-issue for me)

 

[meltmylungs_]

bump