This is something that has been requested since the release of the game by a lot of people (there are quite a few areas where Dark Urge feels incomplete due to lack of companion reactivity) and at this point I just don't think it's ever going to be fixed.
It saddens me since other things have been added with new animation and voice lines (evil endings, better reactions to Astarion running from the sun, new Ansur cutscene) but the Dark Urge stuff was just ignored.
