Originally Posted by Reaper16
"experienced ear for clean vocals"
that's about the most self-interested way to phrase a preference I've seen in a long time.
Seriously though, metal needs more clean vocals? There are plenty of bands that do great clean vocals. Plenty. Unless you're insisting that the subgenres that utilize harsh vocals begin to produce bands that use clean vocals. To that end, I'd ask 'why?' There's a bit more room in black metal for clean vocals, but those bands have to be heavily influenced by folk or post-rock or etc. to make it work (basically, then need to be Agalloch worshippers). Clean vocals in pure or Technical death metal would be awful; the harsh vocals are utilized in DM because the vocals are a rhythm instrument in that subgenre.
On the subject of clean vocals in Black Metal, have you ever heard of the band Ulver?