The Hobbit Trilogy codifies the Star Wars prequel formula can be applied to any popular franchise as a template to tie-in. Even if you’re not an expert, you can picture which parts of prequel sagas are marketing for the originals or stand-alone content like movies should be. This means The Phantom Menace was just a prelude of what The Hobbit became and Fantastic Animals could become.
If you want to adapt a novel in three films, the logical process is a movie each act. The Hobbit doesn’t follow a consistent three act structure because most of it has plot-irrelevant obstacles until the dragon. An Unexpected Journey has everything you want in a Hobbit film and leaves almost nothing for the sequels, but uses filler to establish “relevant” aspects in the future.
I haven’t seen the animated Hobbit yet, but probably won’t be a marketing strategy to announce pre-established films and shows that a duology would be enough to outshine this adaptation. Just two movies make perfect sense and Guillermo del Toro wanted it like that when he was going to film them. I like Desolation of Smaug the most for having more consistent rhythm, the best action pieces and character development (and a shitty love subplot). To bookend, Battle of the Five Armies is so ridiculous that looks a self-parody.