Luke has probably come to realize what incompetent boobs the Jedi were. They let a Sith lord hide in plain sight, Yoda and Obi-Wan both trained Jedi that basically destroyed the Republic, they used a slave army of clones that were so brainwashed they turned on the Jedi and destroyed them in battle, ushering in the Empire.
Freegards
One of the great questions of SF: when there’s thousands of Jedi largely ruling the Empire in the open and 2 Sith hiding why in blazes would the Jedi want to bring balance to the Force? But the prophecy was right, Anakin knocked it down to 2 of each, very balanced.