The "New Republic collapsed in 1 DAY" totally destroyed the ST's world building
TFA didn't start well and TLJ totally settled it.
Even the old Republic require Palpatine to take years to change it into the Empire. Even the Empire took the rebels years to take down.
New Republic died in 1 day, simply because a capital was destroyed? It's just super nonsense. And First Order didn't have the same level of intelligence/moff to manage the system.
We can also see how hard Disney tried to fill this hole in their new canon, like making the New Republic super bad and First Order already took a large chunk, but it didn't work. So overall, ST era was not expanded because it got little potential.
Even though the PT got many flaws, its world building was great.