I think its more about the work they implimented for motion capture, voice acting and so on for the existing companions, with all their quests and background etc. Its a lot of work, a lot of money, so they dont want new players to have full customs from very early on (depending how soon they find withers) so the whole work isnt wasted. (i think)
Meeting in the middle would be nice here, lock it behind an achievement or something when you have completed all companion arcs or act 3 at least 2 times or so.
