1. The feud for the WWE belt, which is considered the center of the main event, is between an unproven main event draw last seen losing a match for a lesser belt and someone no one has cared about in a main event capacity for at least a decade.
2. The real main event is contested by two part time acts that can’t be bothered to actually promote their fight.
3. The only person WWE has taught their fans actually matters has meandered aimlessly carrying a title the company has portrayed as a joke for years, and he has no meaningful feud on the horizon.
It’s not rocket science.
As for #2, that’s totally on WWE. Brock Lesnar doesn’t get out of bed unless they cut him a cheque and presumably deliver it to his cave via Pony Express, so if they don’t want to spend the money to have him promote the match then it’s not on him to do it on his own. This isn’t UFC where he gets PPV bonuses if he somehow draws a million people.
As for #3, yeah, I really don’t get the Cena thing. What was the point of the Seth Rollins feud, anyway? To fill a couple of months? To beat your World champion a whole bunch of times to put over a guy who’s been on top for a decade anyway? Well, mission accomplished.