The PC is not a literal god. S/he is the fragmented reincarnation of a precursor famed for their strength and generosity upon whom some gods were based, but even Azem was not a literal god (in fact current signs suggest there is no such thing as a true god in the XIV universe, despite the known Ancient true names all being Olympian deities). The PC has simply inherited Azem's strength and generosity, and uses it to help others across the world(s) as his/her ancient incarnation did.

Reducing the power level is not an easy thing to do. Once you're effecting things on a given level it's difficult to narratively regress from that scope. WoW tried to do it with Battle for Azeroth, but among the many problems plaguing the expansion was how you went from fighting the literal legions of Hell to dealing with relatively low-key problems and kicking around the other faction. A hero whose strength was lent to ending the threat of the Burning Legion forever is way too powerful to call on for dealing with a witch coven in the woods, yet lo and behold that's exactly what ended up happening. (The whole faction war was only a thing because the writers were willfully ignorant of the Alliance gaining command of a starship!)

As for this game... we've been agents of the Scions since ~Lv15, our actions saving many lives since and effecting the fate of nations at Lv50 (2.0's ending). Regressing to being just a good-hearted mercenary would be a very difficult thing to do, particularly after Shadowbringers. If our allies are able to overcome the threats at hand without calling on us, what would be the point of us being there?