It insulates them from politics (What a joke, but oh, well.) but keeps the court from being dominated by dottering old fools or nominations made exclusively of people in their early 50s.
Makes sense to me, AmishDude. Of course, this change would require a constitutional amendment.... How would you rate the prospects that Congress would ever initiate such an amendment? It would take two-thirds of both houses to agree on the amendment before it can be sent to the states for ratification. Alternatively, the legislatures of two-thirds of the several states can petition Congress to call a Constitutional Convention. But such a convention would not necessarily be limited to the business of amending the terms of members of the federal bench. People might fear such a convention might open a whole new can of worms....
Either way, Congress then decides which Mode of Ratification will be used: (1) either 3/4 of the Legislatures of the several states, or (2) 3/4 of the Conventions of the several states called for that purpose.
Congress historically has followed the first ratification route. But if they seriously wanted to "muddy up the waters," they could instruct all 50 states to call ratification conventions of their own.... That ought to slow things down -- a lot.
Sigh. It all comes back to the same problem/cause: Congress' penchant for extraconstitutional or unconstitutional exercise of its Article I powers. The Left is dedicated to strengthening the courts at the expense of the executive. I don't see that the Left in Congress would find anything particularly advantageous in limiting the terms of federal judges and justices -- i.e., the power of the courts.
Just thinking out loud.... sorry