Wouldn't you say that longing for something (an ideal, for example) is an emotion as well?
Pop-music doesn't express such a longing-emotion. It creates an empty space, for the listener to project his own emotions into. It's not about what the 'artist' wants to express, but about what the listener wants to hear. You get sort of an emotional experience out of it, but it's a superficial one, because you don't have to work for it. You don't have to actually listen to the music, you just have to 'feel it'.
Does that make any sense? It's like the difference between working for true happiness, and snorting a line of coke, because you want true happiness now! Both will get you happiness, but one is lasting and substantial (it connects with reality outside your head), while the other is short and superficial (it's just your brain on a stimulant).