I think some named Elven characters would be needed (yes, even in a hypothetical faithful version). I mean, Elves turn up quite a bit in the book, but are mostly referred to collectively : "they said this", and "they said that". That would probably not work in a film. So I've got no objection to PJ throwing in an Elf-maid named Tauriel– as long as she's a minor character, and not another version of "Itaril".
Here's hoping the change of name indicates a change of plan. Jackson has supposedly said she's
not to be Leggy's love-interest, which reduces the Mary-Sue factor somewhat.
On the other hand, there's speculation she's going to be
Bard's love-interest...
Oh, and though in every reference to this new character on the net, she's "Tauriel, daughter of Mirkwood", the name doesn't, in fact, mean this at all. Wonder where that came from.