They're never gonna make casual content harder because it will destroy the casual playerbase of the game.
They specifically designed casual content to be as face-rolly as possible, and the few fights with dps checks in the game have echo built in.
Even EX dps checks have very forgiving dps checks where you can just die 12 times and still clear.

If you wanna be challenged, come and do Savage and Ultimates. It's a lot more fun than casual content imho.