The problem is that France, even if it has no navy, can march across the strait and completely occupy Great Britain if the UK doesn't put a ship in that sea zone. But that also brings up a different problem, the UK never stations enough troops in the mainland, making them too easy to crush.Right now I mostly play Arkham Horror, Agricola, Diplomacy, Mansions of Madness, Axis&Allies... so a mix really. Favorites vary a bit but nothing beats Axis & Allies 1940 with both boards combined.
The strait was added because there was no time to work on naval AI, pretty much. Nobody was happy with the solution but it made the British AI more active in Europe so I felt it was a lesser evil.