They probably see and glance over what people want, but using concepts? Naaaah they've got a team to actually design these things, they might hand them a short list of the things people are discussing but at the end of the day its the job of designers to design not copy.
I'd also say they probably pay more attention to what people are speculating about when it comes to advancements of the current classes, because at least then the audience is already playtesting the content and not just theorycrafting hypothetical content.
