I've argued for term-limits for SCOTUS justices in the past, and I'm glad to see advocacy for it on the left (Yglesias) and the right (Douthat).
My reasoning is not the same as Yglesias's. I hope that term limits would lead to a little more humility on the court. It could also allow disastrous justices to be only short-term disasters.
I think term-limits in Congress would do a lot to cut down on the arrogance and the b.s. that follows from careerism. We could use a few more people like Cincinnatus and fewer unprincipled, self-aggrandizing bags of bones. (95% of the Senate, you know who you are.)