For many people in HaloGAF, at least those who were around the time when Reach launched, they attributed the fall of halo to Reach.
Reach's decisions alienated the community. MLG dropped Reach and competetive Halo was shattered. Community was divided on the bloom and AA's but the overall gaf consensus was fuck bloom and AA. BTB was a mess. Customs lasted for a bit but died out. Halo 4 was worse. MCC doesn't work.
Pretty warm reception to H5 beta tho so..... hope?
I guess it comes down to how everybody plays Halo. I don't care at all about MLG or the competitive community. I like BTB with friends, and I loved Forge World in Reach because it allowed for a bunch of permutations without Bungie having to explicitly design new maps for the playlist.