Horrible idea. You could be putting yourself in a situation where you and the car are unable to safely stop if the car you're following suddenly stopped. It would be pretty silly to allow a TACC following distance that is guaranteed to result in an accident if the car in front stopped suddenly, then have the car in front suddenly stop, and accident happen, and someone blaming Tesla/TACC.
Never going to happen. The car is always going to maintain a safe distance even on 1. If the car can't stop in that gap in front, it's not going to follow that closely, period.
Basically, what you folks who are complaining that it is too far back are actually saying is that you don't drive safely to begin with.
I personally leave TACC on 7. Safer, softer stops, etc. If someone jumps in front of me, so be it. Doesn't hurt my feelings. I'm a huge supporter of "KEEP RIGHT, PASS LEFT."