Somehow, I doubt they pulled out of showing better visuals of the Sundering just so they'd have their budget for hamburger eating cutscenes.

For whatever reason, they decided to keep it vague and not tell us what happened.

If they were going to show it, they surely would have budgeted for it first and foremost.

Either that or they did make an animation and it fell victim to late changes to the plot and had to be thrown out.