What about repairing/replacing existing components?

I agree that not everyone needs an i7 desktop. However in a desktop the components can be removed and replaced relatively easily.

You need to replace the motherboard? No problem with a desktop, just disconnect, swap and then reconnect.
In a laptop? Good luck with that.

Power cord has been cut? No problem! Simply buy a new $15 dollar cable.
Charger cord has been cut? That's at least $80.

DVD drive busted? Replacements are easily found at your local electronics store
Laptop dvd drive busted? Send the whole computer to the manufacturer and hope they can replace it or by an external DVD drive.  

Main screen damaged? Simply purchase a replacement and hook it up.
Laptop screen busted? Same as above but lose portability. Otherwise throw it out.

The list can go on and on.