Yes.. I did read.. Refer to Sw1tchFX post. Same thing. You dismiss his analogy without actually thinking that the real answer is right there in front of you. You want it in black and white so that little thinking is required.
I'll make it even more obvious... Fiesta and DB9 are both made of metal parts... yet you still can't see the difference? You don't need to be a car enthusiast nor in the market in purchasing a camera to figure out.
The 1 series is much more expensive for many reasons beyond just the build.... what type of answer are looking for? That the magnesium in one camera comes with a special magic formula that translates to impeccable composition no matter the photographer behind it? What? Your OP is already making a blanket statement that the magnesium in 7D and 1 series is the differentiating factor in price... incorrect assumption. You put two sentences in formulating a broad question and yet expect anything more than short answers in response?