"To kick (someone's) ass" is slang, and means to beat or dominate someone in a fight. The phrase has moved to a figurative sense: "to win/supersede", "to dominate" or even "to make a strong (positive) effect". "To kick serious ass" roughly means to present itself in a strong and influential way. To be "great". Actually, it's used as an adjective that way: "Liam wrote some (seriously) kickass tunes." = great music.

No it's just a way of describing popular music.