It is a photo ID and it proves US citizenship.
It is something worth having for all US Citizens.
I have mine. Ya never know when you'll need one on short notice...
Thought about that when Kalifornia looked like they were ready to hand over the roads to illegals. My passport had expired, and I collected papers to get a new one. I don't travel often, but figured when I do I don't need to find myself in a state that has rescinded reciprocity and no longer acknowledges my driver's license as valid ID. Ended up collecting signatures against the effort and more than enough were collected. State legislator critters didn't really want to see the measure on a ballot and it tumbled but it's back in the works ... and so is my passport application.
Like you say, it's something worth having.