Well John Mayer's Waiting for the World To Change has a light hearted feel to it too. Kris though I think shouldn't be smiling for the lyrics. He needs to learn not to do that.... So I don't know...?
As for range, I disagree that range determines what singers I like. I think that's frankly ridiculous. There are other things like tone, control, and style which also determine what singers a person likes. Music is a very subjective thing....
In Adam's case, I think he has amazing vocal range, but I'm not in love with his style of singing. And YES, that affects whether I'll listen or buy his freaking music.
Some of the best artist's of all time haven't had the best singing voices. Bob Sager not exactly the best singer, but wow Have a Little Faith in Me, We Got Tonight.
Music is more about what moves people, than vocal range. It's the whole point of art.
And I think that Adam is an AMAZING talent.