I don't know for sure why they haven't done it. A big part of the reason, of course, is that Congress was controlled by Democrats up until only a decade ago. Since then, moderate Republicans have joined with Democrats to maintain an effective majority against these kinds of legislation. I think another part of the reason is the media-induced public view that the courts are the only thing standing between venal politicians and totalitarian madness.
I don't think it would be that much of an exaggeration to say that if people understood the true nature of judicial activism, legislation like this might not be necessary.