I think that if so much of the forum in all the languages reacts in such an unusually large way (which Yoshi-P implied) then it's a good indicator that something's wrong.

If so many people on the forums are pointing out the legitimate criticisms with the proposed merge plan, and that helps these concerns get across to Yoshi-P, then it doesn't matter if the voices on the forums are not 100% representative of all ff14 players.

It's not about popularity or getting an accurate read of the playerbase's feelings, it's about considering the real pros and cons of each server merge option.