Carnival putting the old ships from Norfolk, Va?

Why does Norfolk port in Va get the oldest and smallest Carnival ships? They made a huge deal about the Sunshine sailing (arrived this week) and it was formerly the Destiny from 1995 that also sailed from there. The price point isn't as cheap as one would expect, I was able to find a cheaper deal with a ship coming from Manhattan and that one was built in 2017. At this point, even with flights, it's better to sail from other ports.