Disclaimers:(Which I am sure I will need to repeat myself in this post later, but here it is anyway)
First of all, I know, there is an official post about that, but I want to go through a lot of stuff, and necroing that post with a long reply is probably not going to get enough attention it deserves.
Second, no, it is not decided yet whether to update or not, the sole "decider", Mevans, have yet to make a final decision, so the discussion should and will continue on, until a final decision is made, not by me, not by you, by Mevans
Third, the "popular" opinion that, those of us who want lotr mod to update just want to ruin the game, is false. And this post is going to explain why it is worth the time.
Alright, with those out of the way, let's go through the versions one by one, and see what each of it brings to the table that will improve the mod gameplay greatly:
1. Bountiful Update (1.8):
Underwater Temple. The sea is barren in 1.7.10, so is lotr sea biome, a new underwater boss should be welcomed. as for "lore breaking", we can have llama, we can have one-eyed fish
2. Combat Update (1.9):
Shield, Tipped arrows and dual wielding. An actually working shield is amazing, but dual wielding is so much more than just shield (https://minecraft.gamepedia.com/Tutorials/Dual_wielding), it is a great QoL update if you know how to utilize it. The many tipped arrows are a great addition to archery too.
Also, two men boat, enough said.
3. Frostburn Update (1.10):This version adds little, nothing game changing, but auto jump is a great QoL improvement. (Also, everyone can appreciate polar bears)
4. Exploration Update (1.11):
Treasure maps and /locate: Maps/command that can be used to locate nearby generated structure, I can't stress enough on how this will change and improve lotr mod, and people familiar with this mod will appreciate it
5. World of Color Update (1.12): I'm not a big fan for this update, but I am sure the builders can appreciate the more colored options of building material.
6. Update Aquatic (1.13): More aquatic update, like in 1.8, we need as much as possible playable contents
7. Village & Pillage (1.14): This is the version that changed vanilla. It is up to personal opinion on whether you like 1.14's invasion and trading system or lotr one, but since it is my post I will say that the 1.14 systems are superior due to the fact that: 1.You can trade with almost every villager and each got their own profession, you have a way bigger potential market to buy or sell your stuff than relying on the few stationary traders and randomly spawned traders. 2. Trading system of 1.14 has actual leveling mechnic. 3.The invasion of 1.14 is also less dependent on the randomness, you kill a warlord of enemy faction, you get bad omen statue, and you expect a revenge invasion. Integrating the 1.14 village system with lotr faction system is gonna be perfect.
8. Buzzy Bees (1.15): Not just bees, but also a ton of bug fixes.
Sure, we already have some of the things in lotr (like armorstand, different wood doors, sponge etc) that appears in later version, but instead of trying to work on every new mechnic and block by the modteam itself, they can just use the original functions in newer minecraft updates. Also there is the fact that the community can do a whole lot more to shape lotr mod to their own liking, there are many "editor-ish" mods that can alter great many things (biomes, spawning etc) of a mod in the newer minecraft version, and I can confirm that those mods in 1.7.10 does not have nearly enough functionalities to edit the lotr dimension, in fact most of them downright can't touch a mod dimension at all. Also, don't forget that Mevans himself admitted there are many handy development tools at his disposal in the newer minecraft version.
I know updating to newer version can be a daunting task, but I belive in the long run it will save more time than it "wasted"