Mistwell
Crusty Old Meatwad
I'm agreeing with @JeffB too. 5e so far is, IMO the most catering toward nostalgia and taking only the most financially safe steps edition.
I think, but it could be just my personal bias, that this quote is his justification and rationalization for not making setting and lore books.
If you don't want to make anything that was done before, well, you won't make an awful lot of things. Besides, his reasoning, that "reused" material wouldn't be interesting, because people seen it before... Well, what about the new gamers, who didn't? What about them, who wasn't here for the 2e era, or even for the 3e FRCG? The material would be completely new and interesting for a LOT of people. It's just no in-line with the game's focus on new gamers, reasoning not dong books because old fans already have that material.
They're selling the classic books from past editions as PDFs on their site. If people want one of the several manuals of the planes, which were mostly non-crunch material anyway, they can still buy any of them.