I would find it VERY surprising if those colour choices were purely accidental, wouldn't you? On iOS, messages were always green, until the introduction of iMe

I would find it VERY surprising if those colour choices were purely accidental, wouldn't you? On iOS, messages were always green, until the introduction of iMessages. The blue colour is therefore associated with newness. Like when you open a skeuomorphic iOS 6 app and no matter if you like the interface or not it's associated with an older.. dare I say "dated" look and feel. On Android I don't know the history, but I do know that grey is definitely less vibrant than green... grey is dull, faded, old, etc. I mean, we can argue about the size of the impact of these choices, but you must agree there was some intention to them.