I think many people think 니켈백 is generic but I also think that people say they hate 니켈백 mainly because it's become cool to hate them. That being said, I actually like some of their songs and I don't think they're really as bad as everyone says they are.
Personally I don't care for them, but from what I can understand, it's mostly because people say they're plain and generic yet they're still so popular. The video below describes pretty accurately why so many people hate them, IMO.
posted over a year ago
당신 don't have to like them.. But people can at least "tolerate" them