You mean like this?
Literally 1:19 into the intro after the actor credits
Sure, and we can talk about that
if the series takes that turn. I don't see the point in making a big deal out of potential changes that haven't actually happened yet.
And the thing is, LOTR (and Hobbit) is still simply based on and inspired by the original work; that is literally what an adaptation means. Tauriel simply existing and having interactions with the rest of the characters is already a different story than what was in the books, you don't need her to suddenly find the ring or interact with Smaug for it to be any different than her simply existing in the story and having romantic subplot with Fili and interactions with Legolas and the Elf King. The examples you made are literally no different, and you're just describing what an adaptation already is. Even GoT already made sweeping changes, like Bran on the Iron Throne even though it makes zero sense with him already being the three eyed raven.
I believe LOTR and Hobbit already do credit themselves being based on the respective works of J.R.R. Tolkien, it's already listed so on WIkipedia. Not quite sure why you're suggesting that 'based on' and 'inspired by' are somehow different from being adaptations... they're literally the same thing. Perhaps you are thinking of the word
translation? But I'm not sure that works either, since no film or tv series is ever a translation of any book; they're always going to be adaptations.