Probably just that it would make WM Sorc even worse. At least the current list has awesome possibilities like Conc-less Haste, recouping all spent Sorc points and regaining spell slots.
Granted bad things can happen, but I feel that’s a necessary part of playing a WM Sorc: you take the risk of the bad/ineffective for the chance at awesome.
I doubt anyone plays Sorc for the chance of a 1d6 Damage, BA, Ironman chest beam. Even more doubt for the ability to throw whatever is in your hand.
It’s okay as an “you’ll always get something extra when Raging” ability; but it’s horrible as your “the DM finally let you roll for a surge” Sorc ability.