Because it was well received is D:OS2? Coop has been THE feature for Larian games, just like open world is for Bethesda, or reactive branching dialogue for Obsidian.
Making origins playable not only means that player can pick an origin, instead of making his own character, but that others can drop in and inhabit other players companions. It IS rather clever way of doing multiple things at once - it is a Jack of al trades, choosing versatility over excellence.
