They absolutely, in no way, made Mister Fantastic a "wuss" 🤣
The Illuminati are arrogant and arguably a little ignorant, but they aren't afraid. They face Wanda down after she destroys a legion of Ultron bots. They know she's incredibly dangerous, but they believe they can reason with her, and if not that they can stop her. It doesn't occur to them that she can take them, because they always win.
Even when she takes out Blackbolt, Mister Fantastic attempts to attack her, but a rubber band versus corrupted chaos magic? That's an obvious OBVIOUS outcome to anyone who isn't the Illuminati.
You can call them wasted, or hollow cameos, of whatever you like, but the Illuminati were brave as hell to continue fighting as she tore their teammates to shreds.