It's like a seat belt. They have them in a car so you wear it, just in case. Bull bars come with them, just in case something smacks into your front end, so you have it on there, just in case.
You want to protect your radiator and front end as much as possible, not to mention $150 each side for headlights.
In colorado, you don't need one, but anyone that has ever driven in treed areas, like in the PNW, even on the most popular runs, there can still be branches hanging out waiting to smack the front end. The difference between "tread-lightly" and driving a 4x4 thru a wooded trail is quite a lot.