Everyone wants to see naval battles included in the TOtal War franchise.
However during the middle ages most naval encounters occurred outside of ports, i mean how many times did the Venetians and Ottomans duke it on the coast of Venice, same goes for the Ottomans and Byzantinians outside of constantinople.
What if everytime you blockaded a port, or challenged a blockading fleet you had to fight it out as a battle? It would add a totally new demension to a part of the campaign that isn't terribly interesting. Other than buggering the enemy AI's economy, building a massive fleet is not an awful lot of fun for the ammount of florins it takes i.e. in my current spanish campaign i absolutely dominate the entire mediterranean but building massive fleets of carraks has pretty much bankrupted my treasury.
I could pretty much garuntee that if CA included naval battles as a major feature in the next total war game (im predicting Napoleonic) than they would sell like hot potatoes in a Kazakh winter. It would totally be the icing on the total war cake!