The WWE is doing what they do best. When they can't improve their product and make it more interesting, they simply offer the customer more of the product and see what sticks. Every PPV going forward is now likely to start at 7 PM ET and go four hours. Rumble/Mania/SummerSlam/Survivor Series are all likely to push 5 hours in length.
https://cultaholic.com/news/wwe-to-change-lengths-of-their-ppvs/