No one has actually pointed to anything in Worlds & Monsters which is "insulting". It's a book about RPG design, with a particular focus on the accreted story elements of D&D. Yes, it contains opinions about the strengths and weaknesses of that material, and about the best way to combine it into a playable RPG. That's (part of) the job of RPG designers - to form, and then carry out, such opinions.It's their tone and phrasing some of those writers used in those books. Writing can in fact be deeply insulting. And while it wasn't part of the 4e game's actual design, parts of the designers' PR and Marketing efforts for 4e could be interpreted as being pretty insulting to anyone who didn't agree with them.