It is not ruined if it is timeless, i.e. the latest craze passes and is no longer cool.
Slamming a truck to the ground will pass and the radical frame and suspension modifications are not reversed, thus the truck is not timeless.
Shaving a truck of all of its exterior accessories will pass and the handles, antennae, gas filler neck, tail lights, head lights, park lights, etc., will never be replaced, thus the truck is not timeless.
Updating the systems of the truck leaves many of the vintage parts for the scrape heap, to never be used or found again, thus the truck is not timeless.
To each his own, however in thrity years many of these trucks will be at the end of their lifespan without the TLC of the vintage truck lover. Preserving them is vital to their survival, whereas they are not making them anymore. If a highly modified/customized truck doesn't end up in a museum, chances are the style will pass and the next guy will have other interests, thus the truck gets pushed to the back of the class and soon forgotten.
Long live the vintage iron.