I guess that the AI will not allow you to do this quite as undisturbed in EB2.
The M2TW campaign-AI does, actually, use naval landings from time to time.
Sure, an island will be somewhat more protected from invasion than a "regular" province, but that does, in my opinion, only add realism to the game. After all, launching a naval invasion is not the kind of thing you can do whenever you feel like it. It takes careful planning and preparation.