I must have misunderstood.
When you say ports protect ships, I assumed you meant the ships were “in port.”
For example, in your WWI game (correct me if I’m wrong, again) ships 'in port" are placed on a separate card, not a space on the board. A ship “in port” has all the extra effects you mentioned above.
I consider this much more complicated that simply adding 1 move point. Yes, it’s only a few extra sentences, but you’d be surprises how many times I’ve repeated a sentence to a new player 5 times and still have them either not get it, or claim I never said it.
For most new players, telling the difference between a cruiser and a destroyer is hard enough, much less remembering what they can do.