I realise this was a rhetorical question, but...
People don't value originality 'cause often times its old and it sucks. For example, my 260z came with carburettors. They are original but they are hard to start on cold mornings and suck down fuel and they smelled and stalled around corners. So I replaced them with fuel injection and it has paid for itself about 5 times over in money and enjoyment.
The 14" wheels were also original but lacked traction so I changed those. The rust I cut out of it was also original but I replaced it with non-OEM metal patches. And I changed the original paint cause that was crap.
Now it's a great daily driver and probably a lot happier than being left out under a tree in my yard as it was previously. It's not original but I reckon its heaps better.
Maybe your carburettor was just crap, because my 200B is carbie, and it always starts first shot, never stalls, and isn't too bad on fuel for its age. I'd never replace it with efi, mainly because it would be too much work, and I'd never be able to fix it myself if it broke.
As for the smell, that's just part of the fun. Lap it up. Paint has to be replaced with age, so, resprays are fine.
You're getting a little bit picky when you say rust... I mean, come on man, no one wants a car with "original rust" in it. Unless you can fix it.
Also, there are things you can change on your car to add functionality, then there's just wank factor. You don't really NEED a turbo, bodykits, canon exhaust etc... and personally I'd rather not have them. I mean, you can if you want, but, I'd say in the long run you'll decrease the value of your car. In 20 years time, a totally stock 240Z or 260Z will be a bloody rare thing...