There was a thread months ago, before the movie hit the theaters (try a search for "The Kelvin's uniforms" if you want to check it out.) I think most people just figured that 25 years was long enough that a couple of changes in uniform design and departmental color scheme could have taken place between then and the time of the episodes of the original series.
Mmm, sorry. I did search but didn't find it. I try not to be duplicatin' the old threads. I wanted to start a thread on the medical chick with weird eyes. I thought she was really cool. Of course, there's no image yet on Memory Alpha so I can't illustrate... you know who I mean. So I searched the forums for "weird eyes" and I couldn't find anything. Then I realized it probably wasn't much of a topic anyway. I mean, what's there to say.
"Medical doctor lady had weird eyes."
"yah, that was cools111"
"I didn't like her weird eyes, they weren't cannon[sic], Matt Jefferies says [link]"... blah blah etc. That's what that thread would be like.
Same reason command wore red in TNG: it looked better on the actors.
Er, this is the only theory that explains it. I hear a security dude was wearing blue, too... and those pics from TMP are interesting as well. The Kelvin-era uniforms did look very cool.