Update: Walter Willett of Harvard weighs in on the subject with a lengthy yet easily informative discussion on NPR, expanding on the topic. Such as:
[T]he food guide pyramid that was developed in 1991 really is based on the idea that all fat is bad. Therefore [if] fat is bad, and you have to eat something, carbohydrate must be wonderful. So the base of the pyramid is really emphasizing large amounts of starch in the diet. We're told we can eat up to 11 servings a day, and if that wasn't enough starch, the pyramid puts potatoes along with the vegetables, so you can have up to 13 servings a day. That's a huge amount of starch….
Fat's up at the top of the pyramid, and where it says explicitly "fats and oils, use sparingly." It doesn't make any distinction about the type of fat, and it tells us to eat basically as little as possible….
[T]his pyramid is really not compatible with good scientific evidence, and it was really out of date from the day it was printed in 1991, because we knew, and we've known for 30 or 40 years that the type of fat is very important. That was totally neglected.