I think what you're perceiving is Tolkien's world-building ability. Given that that was his greatest strength and unique as it goes, I don't think the comparison is quite fair. I mean, he submitted Silmarillion drafts for a sequel to The Hobbit before doing Lord of the Rings. I can't imagine any other fantasy author ever living up to the bar he set on that axis, it doesn't mean they can't be better in other ways.