Most of their decisions are around laws that can be rewritten to correct whatever negative outcome was seen in the court. This meets your simple majority and presidential signature standard.
For claims of constitutionality there is still a check via amending the constitution… Which is not far from your proposal of 2/3 of Congress. You just also have to clear 3/4 of the states.
I think the problem is the idiots that are supposed to be the check are fully supporting what the courts are doing–and the idiots don’t actually represent the interests or will of the people.