Nickelback
(media.scored.co)
Their issue was that they were formulaic. There were several videos out at the time that overlapped their songs and the timing was always the same, the bridge and chorus were always at the same timestamp, etc. They weren't displeasing really but they found a formula and stuck with it to the point of tiring it out. You could say the same thing about a lot of bands at the time, but as the most popular, Nickelback caught the most criticism.