I think we can safely guess that skulking as a tactic is taken into account in modern scenario design... so changing the rules might break a fair number of them.
One important effect of the rules on the skulking tactic is that you need some space to make it work as the defender. If your opponent is attacking from just one side, it works fine; but if he can hit you from both sides of your defensive perimeter, you need it to be more than 2 hexes thick or your units skulking from one side will be under fire from enemy units on the other side. Since there are few buildings that are bigger than that, it becomes a possible counter for the attacked in urban fights.
I'd even say it's one of the Soviet problems in The Commissar's House, which seems to be the standard RB scenario being discussed in this thread.