*is surprised no one's mentioned Nirvana or the Beatles yet*
With the Beatles, at least, there isn't really one song that people in general know the best or think of first. Yesterday, All You Need Is Love, Lucy in the Sky With Diamonds, Come Together, Let It Be, Here Comes The Sun, there's a decent bunch of songs that people think of first. I'm looking at the last.fm page
last.fm pagefor them at the moment to see which song is the top, and it's Come Together. But there were periods of time when it was Lucy in the Sky with Diamonds, and Let It Be. It's fairly unusual, in my experience lurking around there, that an artist with no new music coming out sees much of a change in which song is their most popular.
http://www.last.fm/music/The+Beatles
In contrast, take John Lennon. Unless we clone him back to life or something, he's not gonna come out with any new music. Imagine will always be his biggest, most well-known song. Always. But is it his best song? Not to me, not by a long shot.
I also second that Queen is amazing, but Gheb is allowed to not like them.
As far as the idea in general, it's unfortunate, but I'd rather people know and love that one song rather than not know an awesome band at all. Bohemian Rhapsody may not be Queen's best, but it's still an amazing song. I'd rather people only know Queen for that song than not know Queen at all.
Also, on a less serious note, I'm pretty sure Smells Like Teen Spirit is the only Nirvana song.