I believe she needs to have her model updated to the standards of animation that I believe Riot has set our for themselves with the reworks and new champions that have more facial features and expressions to boot. Lux is a long standing fan favorite that should have justice with getting some higher quality animations for her base model of course. The other skins like the elemental one are quite fine in my opinion.
I'd love her to have an 
level update one day. Her base model and some older skins look pretty bad these days, while her newer skins are still awesome.
Honestly, her model is fine. It's far, far better than several other champions who don't necessarily need VGUs either - for instance Lulu.
What I could see happening is, she could get an animated face rig, which I can't imagine would take that much more texture or model work (more animation work than anything else).
