Here is my take on the PT Jedi.
They have taken the events of the past and built a dogma on it that is skewed. To avoid the Dark Side they have forbidden attachments. Rather than teach their students about the Dark Side and how to avoid its temptations, they seem to be practicing avoidance. It relates to other things where in the desire to avoid something those who fear it just say avoid it when in reality what you need to avoid it is knowledge and skills to help avoid it. In the PT this comes down to Qui-gon vs. the Jedi Counsel. The Jedi Counsel want to avoid any hint of the Dark Side. Anakin has some fear. Rather than address his fear, they do not want to train him. Qui-gon sees no such obstacle and is willing to train him. What Lucas told Filoni is that the Qui-gon/Maul duel in TPM was a duel for the fate of Anakin. Williams called the music Duel of the Fates for that reason. Had Qui-gon won, Anakin would have been taught differently and would have had the tools to deal with his fear and attachments. Instead he got Obi-wan who went along with the typical Jedi Counsel methods. Obi-wan blames himself and thinks Yoda could have done better, but Yoda was on the counsel and I don’t think he would have taught what Anakin needed. I don’t think those on the counsel really understood him, just like they didn’t understand Qui-gon.
So the Jedi had gotten off track. Probably recently. Probably in Yoda’s life. Mace feels like the face of what is wrong with the Jedi. How he treats Anakin feels in the story like he is driving Anakin to the Dark Side.
Plus there is Palpatine. He is in constant contact with all these Jedi, younglings to masters, and they are unable to see that he is the Sith Master. Their ability to access the force is weakened. So the PT Jedi are not the Jedi they once were. They are not the Jedi they should be. How much is Palpatine’s direct interference and how much is due to how powerful he is I cannot say. But his influence of these events is not insignificant.
And then the Jedi get embroiled in the Clone War (in ANH Kenobi calls it The Clone Wars, plural). They go from being ambassadors and guardians of peace and justice to warriors. They take on additional titles like General. Even the Padawan outrank the clone troopers.
Now, I’ve heard some complain about the concept of gray Jedi. But now in canon we have one in Rey. A gray Jedi is a Jedi that does not fear or ignore the dark side. This is a Jedi in balance with the force. This is the origin of the Jedi before the rise of the Sith. This is not a Jedi that would necessarily deliberately tap into the dark side and flirt with its temptations, but it is a Jedi who knows how to navigate the full force. Remember, Filoni worked closely with Lucas and many things he did in Clone Wars or Rebels was based on what he learned from Lucas. We get the father son and daughter and Bendu. The father and Bendu are both in balance where the son is the dark side and the daughter is the light side. Then we have the Jedi Temple guards. And while the light saber colors have accidental origins, they have come to have meaning. Red means they are on the Dark Side. Blue are for noble warriors. Green are for those wise in the Force. Purple is for those who are firmly on the light side. Yellow is for those in balance. White is for those who have more than one role. We see each of these colors in the canon sources. The Jedi Temple guards and Rey have yellow. Only Mace, the most extreme Jedi and the harshest on Anakin, has purple. Most are blue or green. Qui-gon, Luke, and Yoda are green. Ahsoka’s sabers turn white after she leaves the Jedi order.
There are some things that have come out of all this that Lucas has said he doesn’t like, but he hasn’t done anything to negate them. In fact as the universe expands, these things just get more firmly established. He has said that the Jedi light and dark is not like the eastern concept of yin/yang, but yet when it is described, it really is. The best I can see is that the world of Star Wars is very influenced by eastern philosophy, but it isn’t quite the same.
So I feel that Luke’s assessment of the PT Jedi in The Last Jedi was spot on, if a bit harsh. The PT Jedi found themselves weakened in the force and called on to fill more warrior roles than their typical guardian one. Rather than deal with the issues, they pulled inward and tried to pretend that nothing had changed (something Luke labels hubris). Luke learned the old Jedi way from Kenobi and Yoda and he feels that this way led to Ben’s fall like it did Anakin’s fall. Luke is a bit harsh due to his own history, but the PT really does show the hubris of the Jedi. They fear to let it be known that their ability to access the force is diminished. So it really is hypocritical of them to refuse to train Anakin because he has a bit of fear. But this is all likely caused by Palpatine and his machinations. He has twisted some Jedi into following him (definitely Dooku and possibly Syfo Dias and later Anakin). So some of their issues might not be there fault, but I think it is certain that the way the Jedi are portrayed in the PT are not the glorious Jedi of the past. They are flawed and no longer as powerful as they once were.
Most of my opinion stems from the PT films themselves. I have not read the books or explored the PT era EU. I have not read the comics. I have just watched the films and TV series. The flaws are not really covered in the Clone Wars, only Anakin’s power and arrogance and weaknesses. But the films to me make it very clear that the Jedi are not what they once were and are a problem. They need a refresh. I’m sure it could have been done without wiping them out, but they do get wiped out and then so do the Sith. Imperfectly in ROTJ and then more completely in TROS.