I dunno, I thought that the X-wing displays were supposed to look more primitive than the TIE fighter displays so as to indicate how desperate the rebels were, like they were using old tech out of necessity. The rebels can use displays of higher quality, such as on the Mon Calamari cruiser, so I don't think it's a design ethos thing. The Y-wings were also beaten up to look like the old workhorse ships of the Rebellion. The problem with using old tech repurposed from an earlier era is that the prequels didn't show these technologies either. Granted that the focus was almost never on a poor planet, but even Anakin's podracer had a display which looked more advanced than the X-wing display.