The failure of the Alliance was thinking that simply destroying your enemy would bring everlasting peace.
To me, a far more interesting ending would have dealt with reconciliation and reunification. Or, at the very least, acknowledge that there will always be new wars, but there will always be those who will fight tyranny. But I feel like neither of those ideas are really hinted at all. Honestly, I think we still could have gotten the same film generally, but a brief epilogue could have at least implied either of these themes. But unfortunately the film doesn’t come to a different conclusion as ROTJ, which makes this film’s existence less necessary within the context of the saga.
Again, I do think this is a fun film, but I was disappointed what they chose to say (or not say) regarding the big picture.
Remember The Hand of Thrawn Duology? Where the Empire’s remnants broker an honest peace with the New Republic? In my personal canon that is the end of Star Wars.
Warning: those novels contain Jedi who do not possess Force Resurrection or Force Teleportation.