What sabotaged the prequels in a larger sense is that Lucas had no adult supervision since he was not working for a public corporation with shareholders and a board of directors to answer to, who could have kicked butt if substandard movies were made that underperformed.
The prequels did well, but in this era of mega-hits, they probably could have done much better if they had had competent storylines and a character who had some quality that made the audience interested in his saga.
The most damning evidence in the box office is that Phantom Menace
did the best out of all three. It got the benefit of pent-up demand and squandered it. The other two shold have built on that lead, especially ROTS, the big finale with the epic battle everyone's been waiting 30 years to see. But by then, too much of the audience had been alienated.
It may sound strange to be happy that the bean counters are taking over, but even the most cold-blooded corporate hacks wouldn't permit the kind of total ineptitude that characterized the prequels. For starters, the scripts seemed like first drafts, and somebody should have demanded a rewrite to whip them into even a craftsmanlike level of competence, nevermind brilliance.
Disney's going to at least shoot for the level of the Marvel movies. Not all of them have been equally good, Iron Man 2
for instance, but that quality would be a vast improvement over the prequels. And churning movies out every few years shouldn't be an issue if its not an issue for all the other action-fantasy franchises.