One of the things I really do like about the latest "Previously on Star Trek" and the latest episode is that there was no attempt at all to explain why things looked different. They just are because they were filmed at different points of time and the show has the faith the viewer will clearly understand that. Trek as a franchise needs to put a damn stop to trying to "explain" everything in universe when it looks different. It causes more problems then not when it's attempted. Explaining events is one thing. Providing a new piece of evidence or conversation is one thing. Giving more context to something is great. A great example of this is Lethe in regard to the relationship between Spock and Sarek. Going out of your way to create arcs to explain why something looks different is to far. Accept older productions had less money and tech to make the show and the new production has more and more advances and call it a day.