Tampa has a Bridge height requirement due to the Sunshine Skyway. She can only handle 180-foot tall ships from the waterline.
Also even if Mega ships could fit under the Skyway there isn't enough room in the channel to fit two ships of that size side by side and so it would have to be dredged.
I live locally, But they have been debating raising the Skyway and or just building a new one to as fit bigger ships. Because the cruise industry brings around 700 million into the port which accounts for I believe about 25% of the port revenue.