My personal feeling is that WWII is still "too soon".
If someone wants to - I have nothing personal against it and don't mind.
However, I think it rubs a lot of people the wrong way, especially if it's being done "for fun" and not a clear reenactment - and I think that WWI and later reenacting faces a good deal of discomfort from the general public, no matter how respectful. They are still very recent and there is easy access to press coverage from both - there is even WWI film footage. I think it's too "real" - given the press and the fact that the uniforms greatly resemble modern clothing, whereas people can see American Civil War or French Revolution uniforms as antiquated and "quaint", something clearly different from the modern world.
I really like WWI uniforms, but I wouldn't make or wear one unless I had a very good reason. I really respect people who have a deep historical interest - I just don't think the general public is "ready" for it yet.