This may well be true. But when the general videogame market that they traditionally rely on doesn't give two shits about their current output, the distinction that you've mentioned in your post above between GAF and the aforementioned video game market becomes highly irrelevant.
GAF may as well be speaking for the general videogame market, with the Wii U's current state of affairs, worldwide.
A blind man could see that WiiU's three major issues are the price, the lack of games and the lack of advertising. All three should be fixed in the coming months as they effectively relaunch the system, people asking Nintendo to scrap the console after a year are mental.
For your second statement I completely disagree, GAF and forums like it are extremely hardcore videogame fans, who disect screenshots and every morsel of information.
Even the majority of people who would call themselves big gamers probably check IGN or some other big news outlet a few times a week, discussions of sales, hardware power, resolutions, 'omg the textures on the ground on Pikmin 3 mean I can't possibly enjoy it' only go on here and places like here.
I feel fairly confident in saying that at $249, with a marketing blitz and Zelda, Mario and DKC, Nintendo could outsell PS4 and XBO combined in North America this winter.
NA is literally Nintendo Land but not at $349 with no big name games or advertising. The reality is that at least 50 million of the 100 million Wii owners have no idea what a WiiU is, let alone have a reason to buy one, that will chance big time in the coming year *IF* Nintendo aren't stupid.