Just by the title, I already know that people are going to cry murder. It's easy to pick on the Hobbit trilogy, turning one relatively short book into an 8 hour epic. And diagrams of how many million per page of the book or minutes per word have been done...and they are all, to put it simply, useless arguments.
Let's start with one clear distinction: Adaptation. Adaptation is not replication, nor should it ever be. We don't need the same exact thing from page to screen. That is the most boring thing we can ever watch. No surprises, no room for creativity. Changes are good. They bring something fresh to the work that we can play with. The problem is, we love the books so much, we are apprehensive to even consider welcoming these changes. And a work like the Hobbit and the Lord of the Rings, there is so much to use, so much history that Tolkien provides, and only so many films that they can make. They have the rights to The Hobbit, The Fellowship of the Ring, The Two Towers, and The Return of the King. That last one? Quite the blessing as it includes the famed appendices--histories and events a filmmaker would be foolish not to pull from. And for the Hobbit, Jackson certainly pulled from those pages. Azog the Defiler, Thror's death, Thrain's madness (see the extended version of Desolation of Smaug for this wonderful bit) the White Council, the battle at Dol Goldur, all of that from the pages of the appendices. Now, this is the dilemma--we would all love to see these events in film, but the only place Jackson can do them is in the Lord of the Rings and The Hobbit...The Lord of the Rings has already been filmed. So he has just The Hobbit to try and fit in some very iconic scenes. And really, who doesn't want more Gandalf the Grey?
Along with adding things, we're also feel wronged when things are removed. Take Tom Bombadil and the Scouring of the Shire from The Lord of the Rings. There was outrage. First, The Scouring would have made the Return of the King not just longer, but incredibly depressing. Fine for a book, but after a 12 hour film? It doesn't work as well. But Mr. Bombadil...look, I hate Bombadil and I always have. He is a giant chunk of uselessness and even declares himself useless. His omission from Fellowship of the Ring helped the story immensely.
Let's look at An Unexpected Journey, which follows The Hobbit more closely than the other parts, and let's look at the novel. If you thought the dwarves were indecipherable in the movie, the book is even worse. Sorry Tolkienists. As much as I love it, the dwarves in the novel have no development. 100 pages in the novel, and even the main dwarf, Thorin, is hardly mentioned. He gets one or two moments to shine slightly more, and is basically just referred to as "the bearded dude more important than the other bearded dudes." Aside from that, we know that Fili and Kili are young, and--mentioned more often than some of the other dwarve's names--Bombur is fat. Like really fat, like "Bombur is fattest and will do for two" kind of fat (really, Gandalf says this). Is the movie great at developing the dwarves? No. There are 13 of them, and even in the book, a good deal of them serve no purpose than to simply be there. But if Jackson removed one....MURDER! BLOODY MURDER!
[The Hobbit: An Unexpected Journey](movie:21016) elevates a good portion of the company. Fili and Kili are not just the youngest, we know that they can be reckless and irresponsible. Balin is not just a name anymore, but Thorin's wise old confident who has a fatherly complex towards Thorin--which is actually quite a wonderful aspect in the films, as the worse Thorin's sickness becomes, the more we see Balin's heart breaking. Dwalin is now a mighty warrior, with anger problems and a large heart--which leads to one of the most painful exchanges of dialog in The Hobbit 3: Battle of the Five Armies. And some of the changes might even be small, but they still help. In Desolation, Oin is a doctor (with a hearing problem). Bofur is a bit of a drunk, but the most sympathetic and has the best relations with other species, whether that be Bilbo in Journey or Bard in Desolation. The only ones who really get jipped in the films are Nori and Dori. In the book, they're basically all jipped.
Which also leads us to Bard. Bard is one of the most important characters in the books, he...(spoiler if you have not seen The Hobbit 3: Battle of the Five Armies or read the book).
is the one who kills Smaug and leads his people against Thorin. And yet in the book, we don't even know who he is until he is killing Smaug. This random dude just pops up and kills the dragon and oh by the way, he's the heir of Dale
Desolation does for Bard what Journey does for Thorin. It makes us identify and care about the character, as we should.
Okay, okay, so some additions might help the development of characters already there, but why bring Legolas into the mix at all? Why create a character--Tauriel--for the movies? Sure, bringing Legolas into the mix is fun for the Lord of the Rings connection, and Tauriel added a much needed female presence, but they are not there for nothing. Our elf leader of the three armies united is Thranduil, who again needs development, and we get that development by watching how he acts towards his son and this elf maiden, and more importantly, how they respond. It's Legolas and Tauriel who make us unsure about how to feel about Thranduil. Is he a dick? Well, yes, he is, but so Thorin and Bard are kind of dicks too. But with Thorin and Bard, we have a lot more sympathy. We trust that they will eventually do what needs to be done. Thranduil is harder to figure out, and his reactions to Legolas and Tauriel in Battle make that dichotomy a character point and not just a plot point. Plus, Tauriel's a freakin' bamf, and Legolas was a lot more brutal in Hobbit than he ever got to be in Lord of the Rings. So, you know, yay for awesome.
What does this all come down to? Character development. This is where the movies excell. Sure, there is a lot more and a lot of additions, but these additions breathe life into otherwise stale characters. And even better, you feel this is you go back and reread The Hobbit. The movies really do enhance the already lovely experience of reading the book. The development Jackson adds is not made up from thin air, they have their foundations in the appendices, he just brings them into the forefront (except for Legolas and Tauriel, I know). So now, Thorin is no longer just a dude in charge. Balin isn't a random dwarf sitting on a rock. Bard isn't a random hero. Bombur is...well, no, Bombur's still just the fat one. Can't fix everything.