An interesting question here is whether Tolkien should
have removed more of the non-Middle-earthish
language and items in TH and the narrator
asides to the reader. It's noted in the Annotated
Hobbit and in Letters that some of these were
removed/changed, but that (I believe) Tolkien
wished he had altered more.
One I'm of (perhaps somewhat like Gollum/Smeagol)
of two minds of is the trolls language. Should it have
been made more like orcs in LOTR?
The difference in dwarf mentality and
behavior is, of course, a clear delineation of
differences between TH and LOTR.
To some extent, Tolkien sought to
reconcile them in Unfinished Tales in the
chapter "The Quest of Erebor."