why morg got a particle rework and not a model update like all other reworks??

Hey! I may not be a Rioter, but hopefully I can explain this well enough for you.

Riot had previously done a texture update on Morgana and her skins, as more of a band-aid to the issue of her visuals being outdated rather than a permanent fix. Her particle and icon updates serves as another patch up, bringing her closer and closer to where she needs to be. This is just my speculation, but these prior preparations will likely lead to a visual update much like Kassadin's, rather than tackling the whole problem at once. Hope this helps!

She's had a VU (I guess she looks smoother/has better colors) if that's what you mean..