On its surface, your argument makes sense. However it ignores the real reasons that many of these places are abandoned in the first place: economic depression.

Social and cultural value doesn’t often directly equate to economic value which means your proposed policy to tear down abandoned property and pop up strip malls, parking lots and luxury apartments owned by foreign investors will likely leave us culturally worse off every year that passes. Perhaps we can do better.

It's also short-sighted; present-thinking to a fault (unfortunately, all-too-common). As an example: many of the Gilded Age mansions that helped revitalize Newport, RI tourism (and, essentially, the local economy as a whole, after the Navy mostly left) were basically abandoned for many years. Nobody cared about preserving the decadent detritus of robber barons (because, as you said, people were more concerned with common economic troubles). Attitudes change and lines go up; the jazz fest brought deep pockets and people remembered you could summer somewhere other than the Hamptons. On the other side of the coin, before Enes Yilmazer and after LOTRAF, they served as a publicly-accessible view into filthy rich-itude. Maybe we head towards another depression at some point, and people decide preserving these iconic relics isn't worth it anymore. But that's not an absolute state, just a product of shifting dynamics which we can't really scope out fully without some distance.

How does legally requiring people to leave up unused "historial" buildings prevent foreign investment, strip malls, or parking lots? These seem like completely different issues to me.

Those things are 'mittel zum zweck' German saying for it's just a necessary medium for the intended purpose.

You don't go to the Cinema because of the building, you go for the movie, friends,. atmosphere etc

Sure. Let the squatters have it if it's worthless it doesn't matter. And while you're at it ban foreign ownership on property.

If age or historicity of something lends it value, then the government can pay to preserve that. It's not right to force a private owner to shoulder a cost that has a public benefit. Forcing the government to pay for it will cause the government to more properly balance costs and benefits.

Are you saying, government with tax payer money acts responsibly?

Are you saying when they can impose burdens without cost to themselves, they won't abuse that shamefully?