There are plenty of reasons to hate car mods.

1. You already mentioned coal rolling. But it’s a top reason to hate.
2. Loud exhausts cause noise pollution.
3. Straight pipes cause air pollution. A severe source of Asthma for children.
4. Some lifts and modifications to exterior dimensions are very dangerous for pedestrians and smaller cars. Same goes for modified blinding headlights.
5. Removing speed limiters are extremely dangerous because that’s untested territory from the manufacturer.