I agree with you, Boo
I've said so many times over, but I guess it's worth mentioning again that Tarkus was the first prog epic I ever "got into" and it's just a brilliant song. I like a lot of what they've done, but - as you mention, they're a polarizing band. It's easy to see what people don't like about them.
Still, I think most appreciators of prog who don't like them, if they could forget Love Beach and gave ELP a proper chance, they would find something to like. Tarkus and Karn Evil 9 are obvious selling points and they have a good debut record as well.
For a bit of fun, here's Keith going knife crazy on his Hammond organ in 1971
I once read he got those knives from Lemmy sometimes in the 60s.
edit :
By the way, that is a godawful picture, yet so fascinating.