Agree wholeheartedly with the OP. Ravenna is unsuitable as a turnaround port. The main attraction in the North Adriatic is Venice, and Ravenna is 3 hours away at best, and a horrible 3 hours at that.
The Bologna mitigation is a bit of a sleight of hand as it may well be nearer to Ravenna, but no-one wants to go to Ravenna as a destination in the first place. It was never included in any serious itinerary before Venice closed its doors to larger ships, so we must always remember the end game has to be a sustainable facility in Venice, entered and exited other than through the ancient city. Any development in Ravenna is short term and the shorter the better.