Until now, all the American song I had heard was that whole body body of popular music that deal with the 57 varieties of forsaken love ... misbegotten love ... love, that was it. Occasionally there was a three little fishies thrown in there but essentially it had to do with a very single, narrow subject matter. And then to realise that there's a whole world out there which can be and needs to be and deserves to be sung about.
One of my complaints about the music that dominates radio (at least here) is how much it flogs this dead horse of the love song to death. I like love songs - but not all the time, and not all the same way. Radio friendly music tends to adopt the same rhythms, phrases, positions, and some songs have reduced themselves to mind-numbing repetition in terms of lyrics and melody.
Songs should go somewhere (or rather take you along somewhere) either lyrically, or melodically. When they repeat the same lines over and over (the radio-friendly hook extended to its logical conclusion) or the same tune, ditty, or lick (again, in its ultimate form, the 'ear-worm' that locks itself into a loop in the listener's mind) they become boring.
The only way then to distinguish your song from the next is by varying (usually increasing) the intensity - louder, faster, or simply raunchier, which is what we see now as well. Perhaps the term "love-song" isn't even accurate anymore, since they're about sex.
And there is a whole world out there that can be described in song, and deserves to be, outside of this very limited ambit. The funny thing is, what people usually want to hear on the radio when they're driving is stuff that won't challenge them to think, and so love-songs it is, not because they're intrinsically less interesting (or easier to write well), but because we are so familiar with the conventions that they're like the old shoes we slip into when we just want to step out for a while to throw out the garbage.