There's an infinite number of reasons something can be wrong: there's only a few it can be right.

Also, basement internet drastically underappreciates the magnitude of effort that goes into creation.

I don't play CoD, but I can appreciate the years of development of work that likely went into this (+ the engine, the libraries, the mocap animations, the sound work, etc).

Is it perfect? No. But it would take an incredibly large and well-funded team a lot of calendar time to produce anything that surpasses it.

So kudos to the entire team at Infinity Ward for making something and shipping!