If you like to tinker and keep your BIOS updated by flashing new occasionally, of course it is absolutely worth it. My dual BIOS on my Gigabyte board has saved me at least once in the past. I take it you have never killed a motherboard during a botched flashing session eh? Well, it's one of those things like carrying a spare tire in your car. If you have never had a flat tire, it may be hard to understand why it is a good idea to carry a spare.
If you don't tinker and never intend on upgrading, then you likely really don't need it, but it doesn't add to the cost of the board much at all, and is becoming standard on a lot of boards today anyway. I would say it is worth it for the company to build the feature in, rather than deal with a constant stream of customers calling and RMA'ing boards because they botched a BIOS update that 99% of the time they didn't need to do anyway.