I would rather hope developers don't make balance decisions solely on people complaining on forums. Honestly, I don't think they do, not in general.
Sure, complaints might make them take another look at a given area, but any sensible developer should have data logged that would show them how difficult the content really is for the community - how many times attempted, how many times failed, how many deaths occurred, etc.
The question, I guess, is whether these particular developers are sensible; well, I'm happy enough with the direction they've taken things so far, so I can't say I'm too concerned. Admittedly, I'm also just looking to have fun, not be a super hardcore "FFXIV is my life" sort of player.