I would say that the stats are the most important part of the Monster Manual. especially for people with a simulationist agenda, as these are the mechanics that enable the players to interact with the fiction in a "tangible" sense.
Sure, but I read fiction and non-fiction for inspirational leisurely pleasure.
This is blatantly false and harmful against 4e to boot. It's pretty clear IMHO that 4e D&D harmonized the fiction of the implied setting to a far greater degree before or sense in D&D. The fiction for the monsters, player abilities, and more were vastly important to the overarching meta-narrative of the World Axis cosmos.