Because someone who does "professional" reviews that are readily available to a lot of people is expected to be more discerning with their impressions than someone who is a casual listener, doesn't know their preferences very well, and has little experience. Someone liking the HD700 doesn't negate all the problems people have described here in depth. It much more likely means they are ok with those problems, or maybe enjoy them. As people in this thread have pointed out many times when describing the treble issues.
You can't reduce a headphone to simply "good or bad". There are always going to be issues, and some people with less experience, or a less discerning ear aren't going to hear them or be bothered by them. And that doesn't mean they don't exist. You can't read impressions from people with wildly different backgrounds and perspectives and levels of experience and try to just get a "bad/good" consensus from them. It's not that simple. Headphones have strengths and weaknesses.
Someone who doesn't notice any weaknesses in a given headphone ought to be seen with skepticism because it means they don't know very much.
I like the passive-agressive approach here: You can like what you like, but if you like what I don't like (and/or what measures by someone poorly), you don't know very much (and/or your hearing's rife with problems or broken).
I think it's rather simpler than this: Sometimes you like what you like, not because your ears are broken or inexperienced, but just because you like how it sounds.
de gustibus et coloribus non est disputandum
I don't need or seek concurrence. I just like what I like, and don't like what I don't. I occasionally review things, but always make strong the point that what I say is only one man's opinion. If you listen to a headphone I like and don't like it, I don't assume you're hearing's problematic or broken. And if you listen to a headphone I don't like and like it, I don't assume your hearing's problematic or broken. I'm sure some headphones I like a lot (or even love) aren't necessarily going to measure well; and, if and when they're measured, the measured outcome (good or bad) doesn't change what I'm hearing.
I will not assert that any posted user measurements of this or any other headphone are flawed or inaccurate. Conversely, I won't assert that they aren't. I've been to the facilities of at least a few different headphone manufacturers, and I've seen some very impressive capacities to measure and objectively assess. At least one company has measurement facilities that take into careful account isolation from ground vibration and movement, as well as isolation from radio and electromagnetic interference by placing measurement gear within a room that was essentially wired up as a giant Faraday cage. I've seen acoustic measurements of many types performed in anechoic chambers big and small. And through it all, I think every single acoustics engineer I've talked to recognizes the vagaries inherent in the different measurement rigs, setups, techniques (no matter how crude or fancy).
I will occasionally get pre-production units (of both headphones and electronics) with measurement sheets included (stuff that's from the lab, and not publicly published). One set of two headphone units (of the same model, one pre-production, the other closer to production) recently arrived with raw measurements printed on transparencies (so that the measurements could be easily compared). I've compared some of this type of data (of headphones in production) to publicly posted independent measurements of the same make/model, and most of the time they look quite different.
Ultimately, I remove the thing from the box, place 'em over my ears (or in 'em), and then listen. And it all comes down to that. I do admittedly find the posted headphone measurements (and the private ones I occasionally see) fascinating; but (in my opinion) any one set should be wielded as another data point (along with others' impressions and other measurements), not wielded as a weapon or a presumed final arbiter of what is flawed or perfect.