Well, the currently approved lander is a modified starship simply standing on some legs. Your solution would work, but it isn’t what will happen during Artemis. Not with the money available (other options were much more expensive), and even if there was more money, almost certainly not under current administration.

I didn’t read the article, just watched the video. But my guess is dynamic interactions of the exhaust gases with the regolith. I don’t think it’s something there’s much data about. Without a landing pad, a landing of a full Starship may be a risky business. Of course the landing thrusters on the tip should help a lot, but still. And now that I think about it, the launch from the surface might be worrying as well. We’ve seen what Super Heavy did to a robust concrete slab without a deflector. Starship is nowhere near that powerful, but regolith is no concrete, and you preferably don’t want flying debris damaging your engines when you’re trying to come back from the Moon.