Most music doesn't suck, because there is a heavily standardized (if often unconscious to many performers) method of making music "work" - the rules are easy to follow and especially in rock music - most people with a passable skill at their instrument can pull it off - they can tug at your emotions or get your adrenaline up because there are methods to do this catalogued by the history of the genre - same in movies.
True this all relies on a moving target definition of "sucking" - I guess what I mean is that most bands are effective within the structured limits they place themselves in.