Why
The hobbit? Especially in the light of further hobbit heros in the Lord of the Rings. If you try to name this book you can see Tolkien's problem: "A hobbit's journey", whilst still maintaining the hook of a neologism in the title does not have the same ring. What would you expect of a book entitled "The Orang Utang" or "The Marsh Arab" or "The Lesser Spotted Howda"? Maybe the title should be compared to "The Liverpudlian" or "The Cockney" which captures both senses: a treatise on the type or the distinguished individual of the type. I don't think either expectation is met by "The Hobbit" and think that this is the start of an off balance feeling that crops up again when Tolkien talks directly to the reader in an over familiar way. "As I am sure you have already guessed" jerks you out of your view-point into being narrated at.
I did not find any type setting errors but there were some oddities of a more semantic type.
Smaug's body fell on the town but then was in deep water.
The escape from the Elfen King's hall in barrels just screams drowned dwarves: there is a suggestion that the barrels might have air holes, but the lids are banged down and the dwarfs are in them for twelve hours or more. Some of the barrels ship water. The dwarves are in a bad way after this but I think it more likely they would have asphyxiated and or drowned.
There is some very clumsy stuff at the very heart of the book, or at least the heart of the work composed of "The Hobbit" and "The Lord of the Rings", where Bilbo is riddling with Gollum.
Apparently
Tolkien knew Welsh, which is probably why the reading is relatively easy, but oh my the howlers to my ears: its carven, carven, carven all the time with him.