I understand the dilemma for the lender and insurers standpoint. That doesn't make it a rational transaction for the homeowner though. It's the lenders money, so it doesn't have to be rational...but this is a discussion board.
To go back to the car analogy (you missed the part about replacing the Camry with the Lexus

), no sane person would insure the 20 year old car at replacement value...they would get liability and call it a day. In our example, they're insuring their $5K car for $40K. I would just drive it in a lake.
If your have a loan, you don't have that choice with a home. You're essentially forced to insure the cost of a home that has absolutely nothing to do with what you're living in, apart from the approximate size.
Lender wants to be whole and not end up with an empty lot, I get that. I'm just pointing out that this phenomenon has been exacerbated by the huge run up in construction costs to where you have some market inefficiencies that I find interesting. Maybe there's a way we can pool our money and arbitrage this.
It's a similar reason that "class B/C" multi-family has been such a solid investment over the past decade. As you mentioned, you can't realistically build Class C because it costs about the same to build a workforce apartment as it does to build a "luxury apartment (Ric Campo at Camden mentioned it was something like 10-15% savings to build vanilla over what they typically do). Since the older complexes are often torn down and replaced with more expensive product, folks that can't afford Class A have limited options.
Presuming the Harold Farb specials on Braeswood have some debt, are they required to insure at replacement value? that would get expensive quickly. I'm assuming they have different rules in place.
Anyway, I appreciate your feedback. It's an interesting conversation for me,