Instead of making things worse for balance. Make things better for balance. If one weapon is considered “OP”, make other weapons “OP” for balance. If some mission rewards are “OP” make other ways to get the same rewards “OP”. This make things worse in a declining population is not going to end up working in an effective manner, unless the goal is to destroy.
Instead of making farmy grindy things take longer, make them be more fun in other ways and places.