I do think it’d be weird to make a prequel trilogy without Obi-Wan finding Anakin and bringing him in to become a Jedi as it was explicitly mentioned in ROTJ. Having Anakin be brought into the Jedi on-screen also allows us an organic introduction to them and the Republic (since we’d be from the perspective of someone from the Outer Rim) through our protagonist.
But yeah, the content of ROTS should’ve been 2 movies, not one.
With regards to Anakin’s transformation into Darth Vader I don’t really have an issue with it. I think most people’s complaints are that what ends up being his main motivation should have been his side motivation, and vice versa.
I feel like my biggest problem is that it should’ve been focused less on attachment, and more on power.
Darth Vader in the OT loved power. He boasted the power of the dark side, wanted to bring order to the galaxy, and even his jokes are him flexing his superiority over others.
The biggest theme throughout the trilogy should’ve been love vs. power. Anakin is a man who can’t stand being vulnerable and craves control. Control over the political process, control over when the Jedi do and don’t act, and control over death. To make himself and the ones he loves immortal so he can be with them forever and never have to fear losing them or losing his own life.
Anakin uses the dark side more and more to learn the secret to cheat death, but the more he does so, the more of his soul he gives up. The less he is Anakin, and the more he is Vader. All of Anakin’s compassion, empathy, and warmth is corrupted as he becomes more and more cold-hearted. He puts on a mask to hide his softness. He gains all the power in the world, but he’s left with so little humanity that nobody could love what he’s become anymore. Padme, Obi-Wan, and the Jedi love Anakin, not Vader. Anakin hates being vulnerable, but that’s when his loved ones love him the most. And that’s the tragedy. Anakin loves being Darth Vader because it makes him feel powerful, but it makes him alone. And eventually, despite still loving Anakin, the people that love him realize that he’s gone.