I do think Yu somehow failed as a designer. Although I have yet to play all his games (hopefully we get a rip of Psi Phy someday), it likely reaches the top 3 of his weakest works, and I feel sorry to write this.
He made a mistake with the vision he picked for the game. You can enumerate all the little things that went wrong (and good) in Shenmue 3 but the problem is global, the problem is design.
In a perfect world, he should have foreseen the consequences of throwing his forces on expanding the scale. This is his job. Meanwhile, Shenmue 3 eventually lacks of taste and emotion.
Sure the game was (rather) fun, but it's not like the fun was topnotch. We loved Shenmue 1&2 because there was a great sense of balance. Shenmue 3? The take is different.
Not only it had design issues but few times it didn't feel a game fully minded by Yu. Was the load of humor really his motivation? I appreciate the jokes but the gap with the original Shenmue was too blatant here.
The way Kickstarter works, from the stretch goals system to the natural pressure from fans & backers, it certainly produced some level of determinism on the whole design. Was Shenmue 3 planned as a (short) interactive movie at first? It might explain plenty of things regarding the final product.
The truth is that, I enjoyed the game but I already forgot my experience. I still have some reminiscence of the ending and the yellow/green of Bailu but honestly that's all. As a result, I'm not sincerly interested in Shenmue 4. Intuitively, it's like my mind fails to view Shenmue 3 as a canon sequel.
I just think there was room to do better with simple decisions.