This is an interesting option! To some degree, I do this already. Ice Girl, for instance, has Ice Control and sometimes makes ice walls to hold back an enemy. I've always had her roll her dice in the power, and then used the result as the TN for her opponent to beat. Simon recently suggested that I could also use her dice in the power as a Rating for the ice wall. One of the cool thing about SUPERS! is that both options work well within the system as written.
Anyway, I think your suggestion here is neat and would make a nice optional rule at least.