> Once something is designated as historic, it's exactly as easy or hard to undo as the future generations want it - you're not binding their hands; you're binding hands of this generation so that the next ones can make the choice whether to continue preserving that particular thing or not.

In exactly the same sense you're not binding current generations either.

The issue is that it's a lot easier to get something designated as historical than to get it undesignated as such or to change the process in order to make it easier.

Moreover, changing it is hard because it's a complicated issue that the large majority of people don't really care about and a concentrated special interest group (landlords who want to retain high rents) does care about and doesn't want changed.

Unless you expect that dynamic to change significantly over time, you're binding the future as much as the present.

> Once something is destroyed, though, that is impossible to undo, no matter what the future generations would want.

That is true of all action and inaction. You can't change the past once it has already happened.

You have to choose for them whether the future gets the old buildings or the new buildings. If it turns out the old buildings are worse, e.g. because continued high rents cause lasting economic damage to the region, you can't undo that either.