Reasons why I personally do not do Legion:
1. All current projects I am working on belong to timeline after wotlk because they were started long before legion. Let's say in times when MoP or even Cata was on retail.
2. You are calling "3.3.5a" pot more than full which is totally wrong. We lack a lot of software. I want to make at least one version of WoW fully moddable. That's why I develop tools for it. Didn't you notice that we can't do custom animated m2s still? That's it. Real modding involves every aspect of development - level design, 3d assets, ui, serverside and even sometimes building custom clientside modules using reverse-enginereed material.
3. Server emulator. Legion Trinity Core can't even be compared with wotlk version in terms of stability and workability. No one here can probably fix it. It requires a big team of programmers working on it daily for a decent amount of time. I believe even professional programmers like schlumpf can't do that on their own because there are thousands of lines of code in the emulator and probably tons of RE you need to perform to correctly make a working emulator.
Nobody is against Legion modding here. Nobody is against modding of any version of the game at all. If you want, you can mod Vanilla, Cata or whatever you like. I do not know why you keep expecting tools from someone handed to you or big gratitude from people after releasing your own tools. Do you simply understand that the entry point into Legion modding is very high now? People do not want to develop tools for everything. That means you people who currently mod it should do it to get more attention to your game version. That's how it worked before and this is the only way it will work. When I started modding Cata was just getting aired on retail. Wotlk lacked so much tools, so we did not even think of modifying smth with different file formats. But people gradually released tools - m2 converter, Mirror Machine and later blender wmo plugin, wmo editor, Noggit updates. Do you get what I mean?
But instead of working on that, sharing knowledge, you expect fame and lots of gratitude from people who are not even interested in it at the moment.