If you are planning to keep a bike and ride it into the ground, then it makes sense do whatever you want to make it suit your needs, perhaps including a really good paint job in your favorite color scheme.

But since you asked about restoration, then, no; you're almost certainly better off preserving as much of the original finish as can be preserved. But again, it depends on your plans for the bike; it's easy to justify whatever makes a bike better suited to your needs, but if your plan is to resell a bike, it rarely makes sense to paint it.