Why is it "important?" It isn't. At all.
We don't actually need to "use all of our resources to try and decipher what exactly is going on." That would be impossible when those "resources" are inadequate towards understanding the full picture. It's been stated many times over that these numbers are not reliable. At best they give a thumbnail sketch of the industry. While they may be of passing interest for what they are, they don't give anybody the tools to "decipher what exactly is going on." And when someone from the industry, like Dan Slott, does occasionally appear on these boards to talk about some real inside information or to put the Diamond figures in context, if that contradicts what some fans want to believe, the reaction from those fans is usually one of "You're lying!" - or worse, "You don't know what you're talking about!"
A lot of fans want to believe that whatever superficial glimpse of the industry that the publicly available numbers give us makes them fit to understand the inner workings of publishing and puts them in a position to be expert advisers. But they don't. Not even close.