I'm not a part of the design process, but let me give my best guess.
Cubicle-7 put out TOR 1E and lost the license, so the same designers jumped to Free League and created TOR 2E. At the time they said that the design goals were to streamline and fix a few things, but essentially to not make 1E obsolete. The biggest difference between 1E and 2E is artwork and setting. TOR 1E had a focus on the Wilderlands, so Mirkwood and Rivendell and the Lonely Mountain. TOR 2E has a focus on the Shire, so Hobbitton and Bree and the like. Since they don't want 1E to become obsolete, their plan was to not just republish 1E material, but instead to focus on other parts of Middle-earth.
Now consider the 5E version. Adventures in Middle-earth covered the same material as TOR 1E, only with a different set of rules. Lord of the Rings Roleplaying has advertised a Shire sourcebook, so looks to cover the same material as TOR 2E instead of the material of AiME. My best guess, therefore, is that if you liked AiME you should invest in LORR because it will add to the world experience. It will probably have very similar mechanics to AiME (again, same designers) but cover new places in Middle-earth.
No inside information here, but trying to connect the dots. I love AiME and have already backed the new game.