The reason you are seeing so many ads is because this type of flying is incredibly popular right now, from standard building and flying, to racing, to photography. They are far more utilitarian than helis or fixed wings. You'll find the ads, and stories on quads in the AMA mag because they are part of the hobby, and they bring revenue into the magazine the same as other hot ticket items. I probably don't notice them as much because I don't own them or fly them, and they have little interest to me.
Although you didn't explicitly say this, it seems that your premise is that if there is less advertising of these items, and less discussions of them in the mag, and in general less attention paid to them, this will somehow benefit our hobby and the AMA?