The long story is that all the fancy animation tools and techniques invented in last 20 years are mostly inapplicable to ZK (and Spring) animations, which is because all Spring animations are code that has to be written by coders in a text editor, rather than artwork created by artists in 3d animation software. This in turn leads to knock-on effects such as people skilled with industry-standard 3d art tools tending to find their skills useful elsewhere, and people with programming skills usually having more important things to deal with.
I had in the past attempted to reduce the nastiness of this situation by making a Blender addon that would have allowed people with no code skills to contribute animations. However, it was still very raw, limited, buggy and difficult to use, and only lessened the programmer work rather than eliminated it. Its adoption in ZK is minimal (one animation: strikecom death) because ZK requires slow to be supported; because it only works on Collada models and ZK is mostly stuck with s3o; and because the one person who contributed animations made with it couldn't code and i did not support them enough.
Also, that addon seems now to be bitrotten; my last attempt to use it myself (for the shieldfac candidate replacement model) quite literally exploded.
The long story short is it's work, and noone is doing it. If you want to take it up, it's yours - blood, sweat, tears, despair, everything you can take!