You can always disable earning XP in the options if you want to do story stuffOne thing I don't like much with the later content the progression through the game is far more fragmented now and easy to miss some of the better content as you level up plus levelling up so rapidly now though somewhat offset by the improved team level adjusting stuff. Wish they'd made some changes to Perez once they introduced The Hollows as well as it gets sidelined mostly now but I miss some of the gameplay in that zone.
I've moved to Excelsior as my old SG are reforming on there by the looks of it.