Maybe it shouldn't be taken for granted? I am vaguely reminded of people complaining about ships whose nacelles looked "too advanced" in ENT, forgetting that these things aren't products of some consistent internal process of technological development, but merely of particular designers' and directors' aesthetic predilections. Such expectations are externally imposed by us on the fiction; some impossibly expect it to match up with their own projected view of what things "should" have looked like prior to TOS and decry it for not doing so, while others more readily and sensibly recast their views to match what actually gets shown. That's no different now than it's ever been. The only one of these that is actually supported at all by the films themselves is the first.