All of those arcs seem to have been addressed to my satisfaction in TFA and/or TLJ. At least one twice already.
I agree that the arcs could have been done differently and better. But the arcs are there in TROS.
Poe was just beginning to be a leader at the end of TLJ. He wasn’t fully arced. This completed in TROS.
Finn really knew nothing about the force at the end of TLJ, though TROS kind of screwed up his force/Jedi arc by doing nothing with this. If he could somehow make the cannons fire at the Star Destroyer using the force without Jannah plugging it in! Either that or kill him at the end.
Rey’s arc in TROS was facing her family issues head on. Rey Skywalker is the end of her arc.
This is very different than where we left these characters at the end of TLJ. It’s arcs, just maybe ones that do not satisfy some people. If that’s the really the case, probably stop trying to make this film into something it cannot be.