[JonPR]

Great question!

IMO, it goes back to the influence of singers like Little Richard, Ray Charles and Sam Cooke, who came from the gospel tradition.

As I understand it, African-American culture sets great store by high male voices, regarding falsetto as particularly sexy - whereas traditional white European culture regards it as effeminate. (Countertenor range was originally sung by castrati.)

But then it seems it works in white popular culture as well. Think about how much those girls screamed when Lennon and McCartney hit their falsetto "ooh"s. Pow, that hit the spot all right!

Then in the late 60s the heavy rock style was established by Robert Plant - another natural tenor, inspired by the black gospel singers - and his vocal style became the norm for rock music from then on (at least the heavy and metal genres).

The point is that male voices pushed to their upper limits connote passion, even a helpless abandonment to emotion. Rock music is all about passion - it has to sound overwhelming to listen to, an immersive experience. Thats the reason for the excessive volume (so you feel it physically in your body) as well as the high vocals. The guitars scream, and the voices do too. It all expresses the powerful confusions and frustrations of adolescence, especially male adolescence. It kicks out the jams!

The first piano player from Dexy's Midnight Runners once told me that their lead singer (Kevin Rowlands) used to deliberately pitch his songs at the top of his range - above his comfort zone - because he wanted that sense of strain that communicated maximum emotion.

There's still a place for bass and baritone, of course - especially in country music: the likes of Johnny Cash, Jim Reeves, Glenn Campbell, even Elvis. In pop there's Neil Diamond. And Leonard Cohen, with his fabulous "golden" bass voice.
In blues, you even had what's called a "false bass" tradition, from Charley Patton to Howlin' Wolf - achieved by adding a growl, without necessarily going very low. (And Wolf famously used falsetto too.)

In folk and acoustic music, there seems to be no special preference. "Natural" voices, in whatever register, are what matter.
Then again, bluegrass has a tradition of "high and lonesome", thanks to Bill Monroe - that keening, nasal sound. Obviously it was natural for him (another tenor), but it also cuts through on recordings, matching the pitches of fiddles and mandolins - that would have been useful in the older recording days, when bass frequencies were not so well reproduced.

BTW, I find as annoying as you do. I'm a natural bass (inasmuch as I can sing at all, which is not much). I can handle Leonard Cohen, in his register. If I sing a Neil Young song I might keep the same key, but I'll be the octave below!