I think it's depend on the route you travel. I would buy if my Sienna have that as an option. I use the Sienna for long distance travel, and usually less busy road (CA 395). If you get in an accident, no one knows.
On the Camry, I don't need it. I use this car to commute to work. 99.9% of the time is I can't go faster than 60MPG. If I involve in an accident, I'm sure at least one person out of million around will call 911.