I've not seen Legend of the Overfiend (and from what I've heard of it, I have no desire to see it either) but it is, indeed, ridiculous to place it in an "essentials" box set.
People who do not have Perfect Blue are indeed, missing out. It is an excellent movie, and with a character who does actually make my flesh crawl as he is intended to (creepy stalker man). However, no collection is in any way incomplete without LOTO. It is a stupid move to place it in the collection.
On the revelation front, I will be buying Gunslinger Girl when I have the money, aswell as Tsubasa, Peach Girl, Mushishi and some of their current releases when I have the chance. It's good to see a company taking our market seriously. Hopefully Revelation will continue like this for many years to come.