- Overall decline in critical reception as seen through Halo 4
Critical reception for Halo 4 was pretty positive actually. It sits at 87 metacritic, which is slightly higher than ODST (which I personally think has the best Halo campaign) and Ensemble's Halo Wars... and significantly higher than the "
really good game" Destiny.
- Overall decline in commercial reception as seen through Halo 4
Demonstrably untrue.
- Poor adaptations of material: Nightfall/FuD/Spartan Assault
These are harmless spinoffs. Nightfall and FuD are no more detrimental to mainline Halo than any other cross media ventures... and amongst such projects these two are actually rather competent. Spartan Assault is a simple mobile game, that you have the option of playing with a pad. It's unlikely to even have the sort of exposure required to register against the series as a whole. The fact that you say Halo 5 is "unimportant", whilst acting like these projects that much of the fanbase will never ever see are going to somehow sink it is hilarious.
- Pay £50 extra to understand the story, narrative systems.
I'm not going to lie... I don't even know what it is you're referring to here. Care to elaborate?
Even without that context though, I'm finding it hard to take such a criticism seriously from someone happy to praise Destiny. I got charged an additional £20 to learn essentially fuck all on that. Should be interesting to see what the grand total is by the time it can count as a complete story.
- The MCC being broken for six months.
This is the only one of your points that has any real merit. Even then it's quite far removed from the overall point you're trying to make. 343i successfully launched Halo 4 with no real issues to a far larger userbase than MCC, and ran a very solid beta for Halo 5. MCC was a pretty unique project handled by numerous studios (generally not 343i), that combines multiple different engines and network implementations into a single product. It having significant issues doesn't really reflect future Halo iterations. Even if the next Halo was to have a similarly complex arrangement, MCC's existence would prevent it the same things from being a surprise the next time around.