I found the critique misleading. It doesn't make sense to disparage Tolkien's Middle Earth writing without taking his background into account. He was a scholar of Anglo-Saxon legends and literature written in Old Saxon, Old Norse, and Old English. He was also a linguist who worked on the Oxford English Dictionary for two years. He was an expert on Beowulf; one of his most celebrated scholarly works is "Beowulf and the Monster Critics".

The writing in The Lord of the Rings and The Silmarillion echoes the style of the work he studied and taught. I understand that many modern readers find the style and language alien; after all, the English language and English literature evolved considerably since Beowulf. Tellingly, the author of the critique compares Tolkien to much later authors, all of whom use ordinary 20th-century (American) English. Tolkien is a modern writer who consciously adopted an older cadence, and the author of the critique does not seem to understand this.

(It's worth noting that The Hobbit and the first chapter of The Fellowship of the Ring use a whimsical, less-grandiose style. I don't have a good explanation for this, except to guess that they originated in bedtime stories for Tolkien's children.)