To me the vibrato/tremelo on the guitar on the opening riff and where it appears through the rest of the song is REALLY irritating to my ear. However, since this didn't sound apparent to the other respondents, perhaps it just bugs me.

I tried to find some live versions of this song and the only ones I found, did not have this over the top vibrato.

I'm guessing that when the radio gods heard the first 10 seconds of this song they went 'nope'. Fortunately for Chris, many of the others were selected and they became huge hits.

I think they could have introduced this sound later in the song, and it would have probably got airplay if they had chosen a less sore thumb for the intro. Or even a less fast, less deep effect would have sufficed.