I have to agree with the original post. I was playing a 1.3.1 install, with a bunch of mods. The performance is rather bad, but the mods make the gameplay a whole lot better. Now I've moved to 1.9.1 and the performance is nice, but several mods have issues, do not work, have changed for the worse, or other.
And so I have to agree that the people working at Squad have had enough time to implement these sometimes fantastic improvements that some mods bring. I'm thinking of KAS, KIS, MKS, base building, interface improvements, a better tech tree, and more. The minor improvements that the current DLC offer is rather disappointing.