I like CK3 sea transport system because if the game required transport ship levies the ai would be physically incapable of it.
While I do think there should be changes to allow for battles at sea between transporting navies, with bonuses for certain units and cultures, I still prefer this system to the pointless CK2 system that created tons of unnecessary micromanagement, or the EU5 system where the AI cannot bring enough of a naval invasion force to avoid being immediately slaughtered by the defending army. I do not want the CK2 system back. There is a reason Paradox made convoys abstract in HOI4 and super easy to procure via decision in Darkest Hour because PDX AI has never been good at troop transport.