Conspicuous is relative to the surrounding. I happen to think that white is most conspicuous because it's brighter than probably anything around it save for anything that's fluorescent colored.
It probably wouldn't be perfectly flat, I think it would have been somewhat fun-house like, I'm using my memory of the G4 iMac.
These statements are almost too ridiculous for words. "Pull the wool", "Looks larger than it is", "The sides look thinner than they actually are". What?! They tell you the exact specs of each model. What is your deal? The black trim has nothing to do with it "looking bigger". (which by the way, I use my iMac by looking at it, and am not constantly thinking about the dimensions of it. If it looks big, that's because it is.) The trim is there to to give contrast between the LCD and the surface. Apple isn't deceiving anyone at all.
Your explanation doesn't ring true to me. Things can appear a different size than they are if the design techniques exploit optical illusions, in this case, I think it does and was pretty well explained be the person you replied to. I really don't understand how you can deny this in such a manner. The perimeter, combined with the black back face also makes the machine seem thinner too. A similar trick was done with the previous generation, the panel was just as thick but the back panel curved forward instead of being flat. The overall thickness was the same, but the iMac seemed thinner, I think Apple even promoted it as being thinner though the overall dimensions were the same.
It's not always the same minority. For example, Aegisdesign had been an almost stead-fast defender of a lot of Apple's design choices, but had lately been hammering on the designs of iPhone and the new iMac.
I really doubt it, unless ALL the testing and validation was done before then, even then, that's a very rapid production.
I think someone posted here two or three months beforehand saying that that decision was already made.