I think the reality with Kennedy is simply that she's always been someone who worked on the money/organisational side of the business, basically smoothing out the business details for people like Lucas and Speilberg and was probably very good at her job judging by how long they stuck with her. She didnt really have any previous history of making creative decisions and so when shifted intot hat era she became your typical meddling exec thinking focus groups and pie charts could make for a good film.
The much bigger issue though I suspect was hiring Abrams and I wouldnt be supprised if that was over her head, probably came from Disney directly. I can kind of see why they did it, they'd just paid 4 billion for Starwars so they looked to Abrams Trek and thought "thats a safe way to get a return fast". The problem is I don't think they looked hard enough, Abrams style with Trek got a positive short term reaction via creating a rather empty nostalgia thrill ride but audiences were already souring on it by the second film and exactly the same happened with SW, he gave them a cheap nostalgia return in the short term but doomed the franchise in the long term, at least in terms of blockbuster films.
Disney/Lucasfilm needed to show more balls the way Marvel have in seriously investing time in building their franchise and treating the audience well. I think you can see with Rogue One and the Madorian its not THAT hard to make good Starwars the fans like that still makes a lot of money. All it takes it hiring talented people who like Starwars not hacks like Abrams looking for new fooder to feed into their cheap formula.
