Is skin replacement better than Bondo for car door repair?

No. There was a time when dents were fixed. A patching compound- commonly known as "Bondo"- was mixed, applied, and cured to form a durable small scale patch for little problems in the vehicles finish. Now, even small dents are regularly fixed by replacing an entire panel (door, fender,...) on the car. This process involves moving large amounts of metal around the country, refining and milling a new sheet of steel, forming and painting the panel, and transporting it back to the body shop.

A bondo patch is perfectly sufficient, far less expensive, and MUCH better for the environment.

It is only a car. Don't be fooled (tricked) into panel (skin) replacement by profit seeking auto repair places. And don't let your ego get the better of your brain.