What's happening here is no different than any other Halo forum has been in the last 3 years. The games have been weaker installations compared to their predecessors and the community becomes separated between those who like it and those who don't (which you see more of on forums). After 6-9 months, the rift widens, positive posters get scared away, and the only thing left is shit posting, circle jerking, and the occasional "favorite" thread. Again, it's nothing that I'm not used to seeing.
Are we really to blame though? 6 months later and there's nothing left other than sporadic attempts at post-game support and a community just now reconnecting previously severed lines. Couple that with the PR disasters and general [online] apathy and you're really only left with a recipe for negativity.
Back when Halo was top dog and the community was vivaciously vigorous, stuff like this was reserved for exclusive corners of the internet, as it should be. But here we are - complaining about the complaints, and the negativity is bleeding out of Halo and into off-topic snides, snarks, and other superfluous topics.
Even if we all put on our sugar pants and wore fake smiles, it wouldn't change. It's okay to be disappointed, but the only way anything will improve is if people start actually doing something positive. We can either play a [Halo] game we like and invite people to join us (like some do), or speculate about what mandible armor would look good on the Arbiter in Halo 5. Either way, we're not gonna have any bones to chew for a while, so it's better not to remain idle.