[QUOTE=Robin wrote and sang “I Started a Joke”[/QUOTE]
Yes he (or they) did. I consider myself a Bee Gees fan but long ago decided the lyrics they wrote were largely a bunch of words that sounded nice together (Not that there’s anything wrong with that.)
But I’ve also wished to hear Robin sing songs with more gravitas and have never found any evidence that he did.
Loreena McKennitt. Her albums are wonderful but live it’s like she’s just come down from the Heavenly Chorus.
Neko Case. She could sing the phone book and make you shiver.
The voice of an angel? Art Garfunkel.
The piano has been whooshing… 
OP writes: Hmmm… many wonderful voices indeed! But most or all of them have been used in the service of singing some pretty weighty (in my very subjective opinion) songs!
Robin Gibb? No so much (may he rest in peace!)
I cited “I Started a Joke” because I always thought it was a very unique lyric for a pop song of 1968 or whenever. You could be right about the rest.
Oh, chocolate Jesus!
I think it’s hands down Karen Carpenter. I’m an unabashed Carpenters fan, and those are some stupid songs. I don’t think anyone else in the world could have made a hit out of “Close to You.” That is one of the stupidest songs ever written.
FWIW, I do think they had a few pretty good songs, but most of their output was drivel. Beautiful, beautiful drivel I could listen to for hours.
Honorary mention is Pink Lady. To be honest, I don’t really know how they sounded in Japan to a native Japanese person, but their US TV show ruined them. Making them sing English songs they had memorized phonetically made them sound awful. Once in a while, they got to sing in Japanese on the show, though. About a year ago, for some reason, I was revisiting some bad TV, and I caught one of their songs in Japanese, and I think I understand why they filled football stadiums full of fans in Japan. I was really moved by their voices when they were singing with expression, and I don’t speak any Japanese.
Carpenter is one of the few people that make Christmas songs palatable to me.
ELP’s Lucky Man lyrics were written by a 12 year old. But man, could Greg Lake sing a ballad.
Now you’re talkin’!
Eddie Vedder with Pearl Jam
For instance the song “Yellow Ledbetter”. When he sings it’s virtually incomprehensible. Then you look up the lyrics and you realize it didn’t matter if you could understand him because they don’t make any sense.
And it doesn’t matter because he sings with such feeling.