Not to sound like a smart a@@, but actually, they are. Here's one example. I own 4 classic/antique cars and one truck. I have mixed feelings on this topic. If it's a rare car, (Hemi, COPO, odd options, low prod. numbers) then by all means restore it. My '69 Camaro hardtop is the opposite side of that statement. It is a base model, no option, non-numbers matching car. It's getting the full protouring treatment. My wife's '69 Camaro 'vert is the opposite. It's an all original survivor that I'll upgrade with original parts, but it's not getting modernized. Nothing that I do to it cannot be put back to stock.
At the end of the day, there's no right or wrong answer. It comes down to each owner. It's a shame to see a nice, original car hacked to pieces (tubbed cars/pro street cars come to mind). The saddest thing is what Barrett Jackson has done to the collector car hobby. Go try to buy a rusted out shell. Good luck.