I remember reading something a while back.
This whole thing (SWGE and Galactic Failure..in short the entire Disney SW strategy) was reinforced by TFA. $2 Billion and Disney thought it was all because of a new cast of characters and "fresh" new story JJ created. Although everyone knew it was a reboot, (I'm convinced early on that Disney knew as well) somewhere down the line the Kool-Aid got stronger for the Disney execs. And they drank more of it.
I think they had convinced themselves that the success of TFA was due to Abrams and the "fresh new characters" that were introduced. And that those characters were fleshed out enough to carry the entire thing forward.
The fact that most people (and nearly all who returned for 2nd, 3rd, and 4th viewings, as is the hallmark for the die-hard fans) went there to see Solo, Chewie, Leia, and the hopes of Luke was completely missed, or at least grossly ignored.
So based on Disney's Kool-Aid moment, they went full-bore ahead. I'm not going to get into a debate about TLJ, but let's say everybody can agree that it divided the fan base. Disney should have realized at that point that there could be a problem. They didn't. They doubled down.
And here we are.