I had this problem attempting to do this in NWN. It is sort of "hard-wired" into us now when you see an isometric RPG to go Diablo style. As a DM I would give some lenience at first but then explain that you are going for the same thing as a regular PnP game and that the consequences will be similar for outright murder-hoboing around.
(Also as I said downstream, without more than 4 players a session, this will die on the vine unfortunately)
