The engineering reason is weight. The Falcon 9 boosters have deployable legs, which are dead weight that need to be carried for the entire cycle and reduce potential payload. I imagine the legs needs for Superheavy would be huge. There may be other side benefits than looking incredibly cool :)It was amazing to see on the stream!
I didn't even know they were trying to do this, happened upon it by accident.
What's the benefit of doing it like this instead of "just" landing it? Is this a less risky way cos it can't fall over and such?