Oh yeah the "vocal minority" that is largely the majority of posts on the internet about these series; you know, the place where anime/manga is even still relevant is as it sure as hell isn't relevant outside of internet circles.
As for buyer opinions you can't even factor them whatsoever when you're critiquing a series. If we accepted buyer opinion was law then a lot of shitty movies would be getting passes as week after week movies that are critical flops makes tons of money and get a lot of love from the masses. This doesn't mean those movies are of quality, however.
Naruto and Bleach are the Grown-ups 2 of the manga world. They're basically low key, critical flop series that are only popular based off name recognization, hype, word of mouth and nostalgia. There's a reason why most people who talk about Naruto and Bleach talk about how awesome it was when Naruto fought Gaara or when Ichigo fought Byakuya rather than talking about how awesome the current fight between Hitsugaya and forgetable-Quincy-character-#100 and the fight between Naruto and Tobi.
I read Shingeki no Kyojin a fairly long time ago when the manga was only a couple of volumes long. It was pretty solid from what I read but had shitty art. But it isn't the next FMA, which people are treating it as.