Going from 120-110 down to 100-90 isnt really a significant decline, it went from unbearably torturous to really annoying. Airports nowadays still create significant noise pollution in their surroundings.
That's like saying the difference between getting stabbed and pushed isn't big since both are physical assaults. It is. 120 is at the level of ear injury and pain even in the short duration of a takeoff. 90 isn't.
Sound drops 4x for each 2x increase in distance from the source. So another way to put it is, if you cut sound by 10x, you are cutting the distance of severely noise polluted area around by more than 4x.