I assume you mean a cost reduction - a nerf implies you would be making the sentry more expensive not less.
I agree. I talked about the interraction between ravagers specifically, and forcefields at length in the past - see here:
But to keep a long thread simple, it’s hard, because on the one hand suddenly being locked out of your base HotS Immortal Sentry style is just awful and previously had very little counterplay, but on the other hand, the sentry is now useless against zerg in particular because ravagers exist, and the entire pvz early and midgame was originally balanced around forcefields.