If a control system is smooth enough that it slips into your subconscious, that's a positive boon for maintaining game immersion. If, on the other hand, you find yourself frequently fighting with or struggling against the control system or the UI, that's positively destructive for maintaining and sense of game immersion.
In this case, Noé seems to feel that the response delay between clicking on a point and having the character move there, as opposed to the zero input delay of direct-driving the character creates a layer between themselves and the game immersion that is a constant awareness while they play; I don't experience that personally, but I can definitely understand it, and I do have a friend who felt the same way when he was testing the game.
Support for different modes of control is never a bad thing; the question, I guess, is how much of a time and resource-sink it would need to be for Larian, and that's something we can't really know for certain.
