...which is in the grand tradition of Disney parks' stuff being initially botched and fixed up later. This is from Michael Barrier's book:
When Disneyland opened on July 17, 1955, Main Street was finished and a half dozen Fantasyland rides were operating, but the other three lands offered only that many rides among them (a precise count being difficult because so many attractions broke down in the course of the day). ... Much of the park ... was bare dirt and empty spaces.
So, the Dumbos knees are scraped. It's a mistake, to be sure, but they'll fix it. No organization gets everything right at first nor did they ever.