It is too valuable to Left to fix, though the Right seems perfectly content to go forward and act. The Right isn't merely agitating, they're trying for policy. The Left aims for outrage and political energy.
"Clearly we have to pack the court!" No. Clearly you have to pass a law. Understandably, that's much harder, because you must actually engage the electorate and build consensus instead of passing the buck to judges to "detect" what the people want, or slant things in your favor by ignoring (or selectively upholding) the Constitution.