I do wish they weren't quite so dismissive of some of the more 'hidden' overarching lore (ie in Frost's books) because there's actually some really good stuff there, and you can see how a lot of the structure, and plot points, are based on (or at least resemble) mythological tales.
They're right that the story is incredibly cohesive without this (and on a similar note I really liked how they showed the clip of Lynch explaining how he likes an in-depth and solid plot that then has abstraction layered over it), but I personally felt that the extraneous material added to the overall experience rather than detracted from it. Much like, but to a lesser extent, how the originally cut scenes from Fire Walk With Me strongly add to the experience. While a lot of those scenes were (mostly) superfluous to the core plot they added an awful lot of flavour to the film.