Certainly in the short run those are more cost effective and less intensive options, but homes built 50 years ago do have a very short lifespan remaining and will consume gobs of energy every day until they are plowed under. Zero Energy refits are cost prohibitive, so at best, you'll have a band aid. Ultimately, It's a sunk cost fallacy.
We're not the solution to the entire problem, but I entirely confident that we are a fantastic value for our customers and the most efficient home available at this price/performance.
Under that assumption, I would have a hard time justifying tearing down an existing home to build a Zero Energy home, as opposed to just implementing those easy efficiency wins and investing the money saved in other environmentally friendly pursuits - perhaps even helping a friend to finance similar changes to their home. Or, letting someone else buy the already built home and build somewhere I don't have to tear down an existing structure.
Of course not everyone would think this way, and people are free to do what they wish with their money, but it's how I weigh the options.