I think you're overestimating the "power level" of the forum. Having an official forum for fans to gather and discuss the game isn't necessarily an invitation for those fans to be the only ones whose opinions will be listened to - or that SE will have to do whatever the forum posters want if they repeat it enough.
Am I understanding right that your plan to "improve" the game is to:
1. Complain about it on social media to damage its reputation and subscription numbers
2. Wait for Square Enix to fix the problems that the game is now known for having, while receiving less money
3. Hope that the damage previously done on social media can be undone - by SE spending more money promoting the improvements?
Were you planning to give them positive press at the end of this process or do you move onto the next thing you're not happy with, further grinding the game's "popularity and reputation" into the dirt in the name of allegedly making it better?
I'm not happy about the reduced number of dungeons either, but that sounds like an utterly counterproductive way of responding to it.
Also, ultimately, the overall number of dungeons is still going up. You say you've got multiple alts covering different classes - I do that, and it feels like there is never enough time to raise them all. I don't personally need more new content at this rate because I'm still bringing at least five characters through old content. I certainly don't need a relic grind to fill my game time, because I don't seem to have enough as it is.
Call me a white knight if you want. But the game as it is is highly enjoyable to me, even if it could be improved, and this relentless "what we have isn't good enough" is tiring. It could always be better somehow, and people are allowed to enjoy the game as it is.
And on being told to go do something else if you don't enjoy the game... I don't see the problem with saying that. Different games appeal to different people, so find one that you enjoy playing rather than sticking around one that you don't like, hoping that they'll change it to suit your preferences. There have been plenty of games I tried and then dropped because I didn't enjoy them.