The similarities in passion evident in the writing between Erikson perhaps reveal a critical element that makes a high fantasy story truly epic: purpose and intent to exercise real-world skill.
Tolkien was a philologist, Erikson an archaeologist and anthropologist. Tolkien's tales are full of linguistic marvels, while Erikson's exude mystery and depth with their complex civilizations, societies, and customs. History is everywhere in the Malazan world.
The key isn't a skill at storytelling, although that's important. It's what you know outside of the fantasy world you're creating that you can flavor it with that gives it the zest and color needed to make it feel tangible and nearby.
If you're a fan of fantasy and haven't heard of them, I strongly suggest the Malazan Book of the Fallen. It's a truly amazing series.