Photo: Captain Kimo, Flickr Creative Commons
Despite the fact that the point of that FiveThirtyEight post is that Irene was appropriately covered based on the level of death and economic damage it caused, the more interesting story deals with Katrina. Based on the author's formula, Irene was the 10th-most covered storm (only counting coverage while the storm was active). It was also tied for 10th based on deaths (21) and 8th in economic damage. Because of this, I'm willing to admit the coverage of Irene was reasonable. There are a lot of people per square inch where the storm hit while still hurricane strength and hurricanes are freakishly serious storms, even the category ones.
Katrina, on the other hand, was the deadliest storm by far in the time period covered in the article, more than 1500 deaths versus the 56 killed by Floyd at number 2. Katrina was the costliest storm in that period, $93.7 billion compared to Andrew's $66.7 billion (normalized). Despite this, Katrina was only the 14th-most covered hurricane during the period the article covered. Remember, this is coverage while the storm is active and not the stories from the aftermath. Katrina received half of the active-storm coverage of the top four publicized hurricanes.
This wasn't because Katrina was a surprise. The storm was huge well before it ever got to the Gulf Coast. It was known well in advance that the storm would likely hit the Gulf Coast. It was also well known by that time that a direct hit on New Orleans of a storm that size would create the biggest natural disaster in a very long time. Several months before the storm hit, National Geographic had a cover article basically saying New Orleans would be wiped off the map if a storm like this hit.
I'm going to go ahead and say that the reason is where the storm was headed. The national media cares about the East Coast the most. California matters second. New York is by far the most important. Remember the New York Earthquake? It was centered south of Washington DC. Is this right? Of course not. The population density in the area around New York justifies more coverage than other localities get, but it gets a little ridiculous when a storm like Katrina couldn't get more coverage than a category 1 like Irene until a city was largely destroyed and more than a thousand were killed.