Keep one hand on the wheel. The way the detection works is sensing a resistance to the torque the system applies. So just hanging a hand on it will provide that resistance. People many times think it is touch or motion based, but it's not. Once you get feel for it, you will rarely get a nag. I use two hand, but sometimes it is a negative because my two hands sometimes balance each other which cancels out the resistance. Having an even pressure or just one hand seems to work better.
Also, as others pointed out Tesla is relying more and more on the camera as people have been calling for that for a long time. It's really the only viable way other than steering nags.
As for Tesla eliminating nags, that's unlikely to happen. If anything there may be more. Tesla is still under investigation by NHTSA, there are politicians still trying to get at Tesla, and there are people/organizations running FUD campaigns to try to get Tesla's systems banned.