Well a Forum is there for these things because there is no other way to tell them what we like or did not like. So of course you will find more people here complaining but saying that they could ignore those is imo wrong. We have Diadem, we have Eureka, we even had the huge outcry about Shirogane housing. The Forum might be a bit more on the negative side but so far it has often been quite the good indicator on when something is not seen as good content.
I mean people running it once or a couple of time does not mean that they like it. It could mean that the rewards for it are enough to make people do it. Just look at Eureka: How will they ever know why people ran that? A lot here on the forum only did it because the relic was tied to it but did not enjoy it, other people enjoyed it for itself. Others just ran it to get the mounts. SE just looks at the numbers of people running it and say that its a successful and fun content and will use that for future content without understanding it at all.
Edit:
Also if you do enjoy the content than that it fine. I for example really enjoyed playing through the FF13 series and yet I know that at least on the internet people complain about it a lot. And that is fine too. Everyone has their right to write their opinion. Does not mean that I will enjoy it less because of that. (I really get the feeling that way too many people let their enjoyment of something being taken away just because not everyone loves it.)
I am also not a fan of this "NA loves to complain stuff..." first we are not all from NA here and such words just take down the opinions of those who post criticism, because no matter how deeply thought out their posts are they are again just complaints and thus bad according to some here.
Please just remember that this is not a fanpage from users but the official forum from the game thus the only place we can say what we think. Also remember that people that take their time to write their thoughts dont do it to punish someone but because in most cases they love the game and want it to be better. And if its all too negative here be the change and create interesting positive topics. If people see it the same way they will post in them too.