NXT works because they write to build the characters. They work to build motivations for everything, and the Takeovers are guideposts that allow them to make big character decisions- though they don't have to wait for those. And if you build it that way, you can make the events seem bigger.

On the main roster, everything is written to build the event. Motivations can be picked up and dropped as the event schedule demands. They're getting better at it on Smackdown, but Raw is an incredibly low bar.