Dawn of War Codex

Why would CSM change their skin to Thousand Sons ones after MoT upgrade ? Even if i use to play as Word Bearers im forced to have TS in my army, because i need to fight HI. The models are good itself but i wish they will stay as separated elite skin pack in army painter.

I thought the whole point about MoT is that they're marked and hence not limited to any particular legion.

Well the upgrade changes the models into Rubric Marines, which are technically a Thousand Sons thing. It was added so that they look distinct.