My beef with EUIV Byzantium as compared to EU3 Byzantium is that they broke the 'blocking the straits' strategy from EU3. Before as Byzantium one could mint like crazy, create a huge galley fleet, wait until the Ottomans were in Asia, and then attack. Now if you do that the Ottomans will just get military access around the Black Sea and eventually come and kill you.
Which is stupid. Historically 'blocking the straits' was a commonly posited anti-Ottoman tactic. It didn't work because Genoa and Venice, the only local powers with the ships to do it, wouldn't, because they couldn't stand each other.
But instead we have in EUIV the Ottomans marching all around the Black Sea, never mind that none of the countries, not even Crimea, would want Ottoman armies in their territories because they wouldn't be sure they would leave. Even in the 1500s when Russia had eaten Kazan and Astrakhan, the Crimeans still didn't like having Turks in their neighborhood because they found them overbearing neighbors.
Never mind the logistics.
So to counter the historical realistic Byzantine strategy of Eu3 (I never did the 'cycle one galley' strategy) we have a unrealistic, gamey Ottoman counter-strategy that makes it vastly harder to play as Byzantium.
It is a good thing this game is easy to mod.
"My Sultan, the Romans are blockading the straits!"
"Don't worry soldier, we will go around the Black Sea!"
"B-But my liege, that isn't..."
"Shh, just accept."