In the past Bungie has mentioned that the way the Taken effect is created makes it difficult or impossible to create it as a shader, and as far as I'm aware all Taken effects on our Guardian in either D1 or D2 has only been on specific armor sets.
It's possible they've resolved those issues, but I wouldn't hold my breath for that to actually happen.
But only those specific pieces of armor had the Taken effects, it wasn't a shader. And just because they've made improvements to the engine doesn't mean they're able to do anything freely.