That's a really good point too, and I think I'd agree with you in some contexts that I wasn't thinking about.

The context of the discussion in the other post was a residential neighborhood. A family living there wants to build a garage to accomodate a disabled person's vehicle and some of the neighbors are unhappy about the look.

Historical preservation is complicated. Preservation itself is ahistorical and inherently makes a judgment about what form of a place is 'authentic', thus delegitimizing other forms of that places's history.