You don't think making the court an explicitly partisan institution by just stacking it whenever you are in power is going to be a bad idea? You don't think it will destroy the collegial attitude of the court that allowed Ginsburg and Scalia to be friends? You don't think Republicans will just do the same thing in response?

Judging by the wikipedia page on judicial leanings[1], Roberts, Kavanaugh, and Gorusch are all fairly moderate, whereas Breyer, Kagan, and Sotomayor are (relatively) more ideological. Only Alito and Thomas are particularly conservative.

And it's not like rulings have always been one-sided. I know plenty of conservatives have their gripes with Roberts.

Democratic appointees even held all nine seats during the 40's, and Republicans didn't stack the court.

[1]https://en.wikipedia.org/wiki/Ideological_leanings_of_United...