The 80x86 command set is an old, outdated, and (by modern standards) flawed set. Intel is trying to replace it with their IA series of processor (slowly, but probably surely while they attempt to pry the backwards compatibility nuts off of the old set with a crobar).
I understand 80x86 is readily and cheaply available, but all it will do is throw the Amiga market into the "every month I need to upgrade "group, which is a place where it will surely be overwhelmed.
I don't care what CPU is used for the AmigaOne as long as it is a modern CPU, with a modern command set, and something that has an architecture that will easily enable moving on to the future whatever that may be (64-bit computing probably). The G4 is an excellent processor for such usage. The 80x86 chipsets are being phased out, and being slowly replaced by incompatible CPU's (yes AMD's still planning on true backward compatibility, but even they've mentioned plans to eventually phase it out)
So G4 isn't "brand new top of the line" as of what 4 months ago or something? It's an excellent CPU, that is going to go down in price due to the new processor line, and puts the AmigaOne on track for relatively painless upgrading.