Now I feel like I'll give my reasons.
Despite me loving the books much more, I think that the LOTR trilogy is a masterpiece that set the standard for epic movies and may never be topped. Jackson's adaptation is masterful, the acting is fantastic, the directing throws you into the scene itself, and every movie feels magical.
Before I get into The Hobbit movies, I wanna say the Martin Freeman's portrayal of Bilbo is magnificent.
The Hobbit was never meant to be an epic, which is what killed that "trilogy". I saw the first movie and enjoyed it, An Unexpected Journey is a fun movie. It's the best of the three IMO because it's not trying to be an epic, it's trying to be a fun adventure movie, and it does that well. The Desolation of Smaug is mediocre. There's no other way around it. The action is good, but the forced romance between Kili and Tauriel the Hated just, ugh. Jackson, we didn't need a wannabe Aragorn and Arwen. It just slows the movie. We didn't need backstory for the Silvan elves. However I think that the ending is the best way to do a cliffhanger. Battle of the Five Armies is another mediocre movie. Tolkien's description doesn't justify making the battle a movie of its own. While I did enjoy it, it just falls short.
I feel like what killed The Hobbit was turning it into a trilogy. Two movies is fine, but you can't turn one of the best children's books of all time into three. It just won't work. It doesn't work.