Halo absolutely has one of the most toxic fanbases for any console game I've ever known. But then it goes the other way - because 343 are first party, people make ridiculous excuses for them. The Xbox One subreddit, for example, is awful for any discussion surrounding Halo. If you think the MCC was bad, it's sour grapes, and you should just enjoy the campaigns (which don't even work properly in co-op).
And on that note, I think you're downplaying Halo MCC. It's more than a shame, death of the franchise in my opinion. They've pissed off their old fans, they've pissed off their potential new ones - and the competition is fierce. AW is genuinely good, and Treyarch are working on the next COD, Titanfall is extremely solid and has the potential to be huge, the new Battlefront treads on the toes of Halo with its sic-fi lore, Hardline is solid.
I can't see any Halo Xbox One game outselling the MCC, unless they literally give Halo 5 away to Halo MCC owners. People have been burned, they have alternatives. All this has come too late.