Captain Friendo
Neo Member
From what I understand it was one of those experimental new technologies rolled out in late 2552, like the new warthog, etc.Except, AFAIK, the UNSC never had any nanomachines prior to... I think Mortal Dictata (or whenever Naomi gets the Mark VII; any Traviss fans wanna help me out on this one?), which took place after Halo 3. The whole "H4 Chief is because Nanomachines" started off with something Frankie said, and I'm pretty sure it wasn't supposed to be taken seriously.
I wouldn't take it too seriously either, but I think it was actually used as an explanation in game informer back in the day, and given that the original Mark VI is still indeed canon, there isn't much else to go off.
That said, the old forward unto dawn look is apparently still canon and we weren't given a reason for why it looks so different in halo 4, so who knows.