Well, but then no stun should be implemented. You can see what happens then, if you play Dota. Stuns are just really powerful, as innociv said, because you can do ANYthing. So if i've to choose a Hero for my Teamup, and i had to choose from Torch / Rook / Remu, i would pick Rook > Torch > Remu.
Yes the slow is good, but the AE-Freeze is better, and the ridiculous low-CD Ae-Stun even more. There has to be more, than only a disbale fest. Knockbacks, silence, slow or roots are a better way to go imo. Keep the stuns rare.