I would like to have naval battles, but......

They need to be implemented correctly so the human player can't cheese through it or take advantage of the AI's cluelessness. If the human can easily outwit the AI ships, that is just one more handicap that the AI has. The human player would rule all the seas, land attackers at will, control trade, etc.

That said, it would be nice to have naval battles (or at least have some clue as to what happens out there). It would probably take a new engine that deals with wind, oars, and various missiles, and have new unit commands for ramming, boarding, etc. Damage to the ship and loss of crew could affect movement, fires could cause havoc, speed affected by wind direction and vessel type.

So many options, but I don't see it happening.