...even though it is by far the shortest of the series.
I think it has a lot to do with the fact that he was writing it as a teenager/college student and hadn't really found his voice yet.
One of the great things about starting to read the LOTR books is seeing how much King borrowed from Tolkien's universe, even beyond the obvious connections, e.g. doorways that need to be mentally conceived into existence, the dark tower, etc...