The disjointed nature of the three films proves they needed ONE director and ONE writer for all 3.
I actually disagree with this. The original trilogy had different directors and writers too - Lucas, then Kershner then Marquand for directing, and while Lucas wrote Star Wars alone, TESB was the work of Kasdan and Leigh Brackett then it was back to George again. What the OT lacked which the sequels had was an overarching vision, in this case the vision of George Lucas.
As I said in my original post here, I see why the decision was made - Disney wanted to replicate the production model of the originals and let each new writer/director build off the work of the last. But I agree it didn’t work out this time, and in any case a series of stories that is planned out from the start is much more rewarding to watch or read than one that’s winging it. I would have preferred a general story outline for all three films before TFA started production, then have new directors on each film to each bring their own visual flair to the story. The sequels’ main problems don’t lie with their direction, it’s their writing.