The sanity change is certainly a decision. I can't see this affecting gameplay quality whatsoever /s. I'm thankful for the performance increase, but I question if a simplified hitbox system on rooms tied to lightswitches wouldn't have been a better happy medium between the two choices, to replace the old method of raycasting light to determine sanity drop.
Overall I don't think that having sanity drop in the garage being stopped if the main room in the house is on is a good design decision.