I don't think it's worth it. Unlike medical insurance, these plans typically only cover very basic treatment and anything more expensive is on you. My job offers 'full medical, dental and vision' but I know the dental and vision plans are garbage, not even worth the $19 a month that I would need to pay. I opt out and instead pay for these things out of pocket.
In general, I like to think of insurance as being for the big expenses I cannot otherwise afford. That cannot be said about dental and vision insurance. I think it's just a offered so companies can brag that they offer full medical dental and vision when in fact it's basically worthless. Of course other can disagree.