I get what you guys are saying about The Last Jedi needing time show the state of the Galaxy, but I think the focus was on the characters. There was no more Republic after The Force Awakens, so why bother trying to explain that needlessly complicated political dynamic? I thought he did a good job just trying to move things forward, rather than trying to explain choices of another director or answer questions that never had an answer to begin with.
To that point, I think the use of Rebels and Resistance are both good together. The Resistance got its name from twisting the rise of The First Order, but now that they have that control, now that there is no Republic, the First Order is becomIng the establishment. They are rebelling against what has been established, and still resisting that takeover.