I think the G5 looks awesome as it stands.
Why do I think so?
Because I think a whole lot of people won't see that it's a computer, let alone a Macintosh. Is that a good thing, you might ask? Yes, that is a very good thing. In my humble opinion, that is. I think it's a good thing, becaue people will see the screaming performance, but won't see a computer and (hopefully) won't hear one too (or at best very faintly).
That, I think, would be a very good thing. Then, when they go and ask "Where's the computer? Or is it an iMac and is the screen the computer?" you can show the baby (or should I say the beast) off. Show the sides, show the sheer simplicity of the design and the striking beauty. Because, yes I think, it's very, very beautiful as it is right now. Although I agree with many here that the G5 should have had two drive bays in the front.
But, after all, that's just my humble opin, er, two (euro)cents.