I partially (mostly in fact) agree with bondovic, I would add however that one way land bridges are still a problem for the AI. Taking the proposed one way Wessex/Flanders bridge for example. There is the potential for the AI's main army or King to invade Flanders and get stuck there with no escape back to the mainland if the battle is lost. It also means that the king loses connectivity with the homeland which may rebel.

Personally I think the default setup of the Wessex/Flanders land bridge is both ok and required. Provinces such as Ireland, Corsica, Malta, Crete, Rhodes and Cyprus also need connecting to the mainland to get rid of the useless islands and make the game more interesting.