Yeah, I kinda agree. I noticed when I was typing the last line. I mean the origin thing makes sense, at least to me. But the Urge argument is ..flimsy. Unless, you actually have less choices as Dark Urge compared to Tav.
Basically, BG3 is made with Tav in mind. The Origins give you background and Dark Urge is a bonus "Path", which has less options because it differs very drastically.
Though I personally doubt it, to be honest.
My impression is they feel that because the Dark Urge heavily nudges players down more evil paths they don't want that to be the first experience because they don't want players to feel pushed down a certain path and do whatever at first...but I was already planning to play more evil paths no matter what and the Dark Urge seems to only enhance and make the evil paths better.