You make the Galleas and Dromon even less useful if they can't move after attack.
My experience with Renaissance navies is the AI build way too many corvettes, which I don't understand because frigates currently don't need iron. They can't hold their cities because they usually can't do any damage to my ships, so eventually I will kill the city. It also means that you get farm experience as you slowly whittle down the city (but I am genuinely killing the city as fast as I can). If you look at my photojournals, I conquer a lot of cities with the 1-range frigates that I couldn't with the old 2-range, no move after frigates. Often those 2 range boats could only have 3 shoot at a city, unless you parked right next to the city, which meant that inland units could shoot me. I could cycle as many as 10. Notably, I took cities that had arsenals using frigates, not cruisers.
Also the promotions for frigates are wack. Targeting into logistics is always the best choice, they do more damage to cities than frigates with full city damage promotions will. I can't even remember what the other tier 4s are, I usually end up just going logistics then bombardment to help knock down arsenals or fealty cities more quickly.
I guess I'm at a loss for what to do with frigates, then.
G