Many would say that the Lee/Kirby issues of Thor are a necessity, but if we're truly going by what is "essential" wouldn't they skip to Walter Simonson's run after that? Honestly, how well would issues by Roy Thomas, Doug Moench, or Tom DeFalco sell? Not saying they're necessarily inferior. They're talented creators and all, but they're definitely not known as the most original or innovative runs on the title.
You could argue the same with titles like FF, Spider-Man, etc.
My question: Are essentials truly going to live up to their name or are they simply going to be Marvel Reprints?