After Hugo, South Carolina and Electric was asked the same question. Their answer - to expensive.
In some areas, I understand that it has been done in some places. Although lines in residential neighborhoods would be buried the large lines that carry the power from the plant to the stations to the customer would still be above ground and vunerable.
My subdivision in SC has buried lines. It was built after Hugo. Most of the ones in the new ones are buried. They have just not changed the old ones. We had people come here to the midlands from the coast. They got hit worse than they would have at the coast. Hugo was a monster that left a major path of distruction from the beaches to the mountains. That is what scared me about Rita. People who were running away from the storm were going to end up in the middle of it.