Some people smoke crack too, so why shouldn't everyone?
Its an individual decision each carmaker makes alongside their corporate attorneys. BMW is obviously less risk averse than Toyota, but they are in the minority. Most carmakers lock out the nav functions when moving.
Complain all you want about that one, its not going to change.
For $299 you can buy something to give it to you. However I will wait and see how irritatiing or serious this is before I buy it.