I still haven't subjected myself to the
TH films, but the plot complications brought by introducing characters independent of the source material, or away from the original author's intent, are well illustrated here, especially when you're doing it in a prequel to films you've already released.
Oh well. George Lucas voided himself all over his excellent original trilogy by monkeying with the prequels in that way, and was none the worse for it financially. Jackson's hardly treading on unknown ground.