I think that Elon likes to drive himself around using alpha versions of FSD, and in a distinctively-painted Tesla. I have no idea what kind of security arrangements he employs, but I think any competent security advisor would tell him to vary his routes somewhat randomly.
It wouldn't be advisable to have his own FSD choose a predictable route every day. So even though he may not have thought of nav-route control as particularly important. I'd suggest that the ability to modify the route would be to his own benefit and safety.
For most of us we'd like to be able to plan and save routes as already suggested, without having to Intervene at the start of every drive.
So the new Waypoints are welcome. I'd like to save favorite routes and name them. Also perhaps some choices to avoid highways, reduce unprotected left turns, choose more scenic routes for touring, and so on. A randomizer feature for selection of routes isn't really necessary for me, but could be helpful for Elon and some of the wealthier owners.