I hardly doubt anyone is offended by the fireworks. They are annoyed that the fireworks woke them up, made their babies cry, scared their pets, etc.
Living in a neighborhood means you have to be somewhat tolerant of certain things; kids laughing or screaming when they are running around playing, an occasional barking dog, etc. But when things are done for personal enjoyment without the thoughtfulness to question whether it will bother somebody else, especially when it is illegal, then it is time to make it stop.
If that 20 year old kid blasts his bass each time he leaves/arrives at his house and it is a noise issue multiple times per day, I will say something. If a neighbor's dog barks incessantly each day they put it outside, I will say something. If you live in a neighborhood and are throwing a large outdoor party that will have music, be noisy, etc., it is common courtesy to invite the neighbors and/or ask them if they care if you are having a celebration that evening and will be a little loud throughout the night.
It's common courtesy. People setting off loud fireworks throughout the night without caring if it will bother the neighbors are unthoughtful, selfish, pieces of shit.