The Resistance had no reason to improve the X-Wings.
This is one of the most disappointing things you’ve said and lazier than I would expect from your usual arguments, can you not see that you’re making an apologist point here with little substance? The movies wanted X-Wings because they were a hit in the past with audiences, the ST had opportunities like this to expand the world and show off a new generation of technology but they decided market research was above something creative and original.
That’s the heart of a lot of these discussions, it’s the stagnation that frustrates fans who wanted to see where else the saga could go after the events of ROTJ, the galaxy can still fall under threat, a Skywalker can still be a dark sider, fragments of the Empire could regroup, but the movies hardly bother to play those out in a way that’s fresh or new, maybe on some technicality but it still feels the same. JJ could have established the Republic’s role instead of blowing them up, the rise of the FO could have happened less off screen. Palpatine’s grand plan and resurrection and reveal could have been compelling but instead it’s brushed aside, Kylo’s mask is restored with greater reverence.