They don't want to have been "fooled" by the marketing, basically. So if they worst-case scenario, and it partially turns out to be some sort of bullshit, they don't have to admit to being excited by the potential of the film.
Or at least, from the audience side, that seems to be the case
From the film-journalist standpoint, it seems to be more about trying to find some sort of angle that reinforces their importance as a gateway to film info: Since the film bypassed pretty much everyone in that section of the media on its way to the trailer release, they have to find an angle that necessitates you look to them for information, and said angle is basically "don't trust this, and don't get excited, and here's why..."