Interesting you consider him technically better, he played a sparse minimal style nearly up until the end of his stint with The Chili Peppers and on his own recordings, which I find to be superior, not nearly as flashy as Slovak. To each his own.

Cooler yes, better artist no.
Also, I don't think Frusciante is in the Hall because he'd quit The Chili Peppers years before the induction and didn't attend the ceremony.