Why are there life-terms on the Supreme Court? Doesn't that incentivize the justices to hold on past their prime, dying waiting for a new president or resigning in a politically motivated fashion? And don't life terms create a race to the bottom where younger justices are favored for longer remaining life? Why not 20 year limits?
The founding fathers thought that the US constitution would look like the UK. President = King, Congress = Parliament. The judiciary was practically an afterthought, and like UK courts, would be subordinate to Congress. “ In all Cases affecting Ambassadors, other public Ministers and Consuls, and those in which a State shall be Party, the supreme Court shall have original Jurisdiction. In all the other Cases before mentioned, the supreme Court shall have appellate Jurisdiction, both as to Law and Fact, with such Exceptions, and under such Regulations as the Congress shall make.”
Note the “such exceptions and under such regulations”.
As history turned out, Congress has barely used this power to rein in the courts and in the mid-19th century on the courts grew more and more powerful and have become a sort of mini-legislature.
James Madison already recognized this, writing in 1788 that he realized a mistake had been made in the constitution: “ as the Courts are generally the last in making their decision, it results to them, by refusing or not refusing to execute a law, to stamp it with its final character. This makes the Judiciary Dept paramount in fact to the Legislature, which was never intended, and can never be proper ... ” (https://press-pubs.uchicago.edu/founders/documents/v1ch17s25...)