In so many aspects of life, it is easy to see the value of diversity. Which is another way of saying it's often bad when everything is the same.
Does that make me homo-phobic? Or hetero-philic? It's never so clear. There's no room for black and white here.
But it's never as clear as it is in modern music.
Exhibit A: ABBA
ABBA would not have been possible without the diverse influences of its two male protagonists. It would also not have been possible without the incredibly tight harmonies offered by the simultaneously perfectly dissimilar voices yet perfectly similar voices of its two female singers.
They were a pop band with a sound that became increasingly synthesizer-driven as they moved (however briefly) through the late 1970s. Yet none of them started out making the music they became so well-known for. It was a perfect fusion of their folk/schlager influences riding on a current of disco music and rapid advancement in synthesizer technology. Even today, with decades of hindsight, very few people can make the music ABBA made.
They are responsible for one of the most perfect pop songs ever made -- "The Winner Takes It All" -- and it's a song that many bands would have been afraid to make. Nobody focused solely on the pop music of the time would have come up with the perfect bassline, which in isolation sounds like the accompaniment to a polka party or a high-brow Balkan pig-roast when you strip it back to what it really is.
And they combined their unnatural synthesizers with the natural tones of real bass guitar and real drums. I'm sure it was just a coincidence that it all started to fall apart when Benny decided to use a drum machine for "The Day Before You Came" (one of their very last singles):
Exhibit B: Death Metal
Death metal is one of the most boring genres of music ever. The music is monotone and the people aren't funny which combined with a difficulty in taking anyone involved seriously is a poor recipe for entertainment. Much of the same can be said of rap music, but death metal is somehow worse because it seems to pretend that it's more than it is.
...unless you're Opeth or Katatonia: two nominally death metal bands who have listened to far more than just death metal, so much so that they eventually concluded they didn't really want to do it anymore and wound up doing a very appealing sort of gothic jazz music (I'm not quite willing to call it "death jazz").
When you have broad influences, you can see how this:
...fits in perfectly next to this:
Exhibit C: Steven Wilson
I'm pretty sure he must listen to everything (including real life), and it shows. So many influences are evident, and all of them are built on toward something new with near-perfection:
"The Holy Drinker" apparently sounds quite random at first and takes some getting used to, but once you get inside its head, you can follow and remember every note:
He even masters the ABBA-style harmonies in a way very few other people can (the key, I think, is that the harmony has to be perfect, but the harmony is never the main point). Follow the progression that begins around 3:00 and ends near the 4-minute mark in "Deadwing", for example:
Diversity is important. Or, at least in music it is.