The justifications roll-on...
Not buying any of them... pretty sure no modern Battleship in the history of warfare has ever been sunk by an age of sail vessel.
Yes... Civ4 is abstract... but it's simple enough to mod even those percentages into something much, much more unlikely to occur then Firaxis left it as. I refuse to allow Firaxis to give frigates a decent chance of sinking modern ships (and Firaxis did just that). Instead of justifying it... I've worked on fixing it.
You seem to believe that your mod brings more realism, and that it is superior to Civ itself. My questions then are simple:
Does your mod make it so that when you take a city, any ships in it are given to you? I mean, realistically, you wouldn't sink ships if you can take the crew off of them.
If a ship is in a city/in harbor, do you use the crew of the ship as a unit to defend the city? In modern times, that's what would happen more often than not.
If the ship isn't given to you, the attacker when you take a city, is it then put out to sea? As if the city is lost, odds are the ship would leave port and get away so the ship at least survived.
If you completely destroy a civilization, do you make it so that any ships and units automatically gift themselves to another nation, or stay as their own nation attacking you in hopes of revenge? That's what happens when a civilization is lost, the people still long for it and fight to get it back, the units/people don't just disappear.
Can you destroy an entire city with a nuclear blast? If you launch a nuclear bomb, an entire city would be destroyed, and few people would survive. Fallout would appear in a very large area, for a very long time, and it wouldn't be possible to get rid of it.
Can you destroy an entire city with aerial attacks? It's been possible to do this for a while now, so I was wondering if you added this feature. By destroy, I mean basically raze with their defenders unable to do anything, even infantry and other gun-powder units who do not have an anti-air attribute.
Civ isn't mean to be realistic, it's mean to be enjoyable and fun, not something that is a battle-simulator for possible future attacks. There are a lot of things in Civ that aren't possible in actuality, but that's because they make the game enjoyable. With your mod, you make it near impossible for anyone behind, by even one tech or one resource, of doing anything defense worthy. Civ attempts to make the game fun and enjoyable, no matter how far behind you are in techs or units. Your mod may be a bit more realistic, but it's definitely not a be all end all. I'm sure there is a lot of things in your mod that are completely unrealistic, but people like you like it because you find it enjoyable, so why knock those of us who find things like a frigate being able to actually do something towards end tech to be enjoyable?