We are dual Canadian and American citizens. The usefulness of citizenships is entirely dependent on whether you plan to live/work in that country. For example, my husband is also a Taiwanese citizen, and potentially we can apply for our children to be citizens as well (I, as the spouse, must live there for two years). But we haven't because we don't see the value in this. Also, our son would be up for mandatory military service, which means that every time he enters Taiwan after a certain age he must visit the appropriate government office to register as a Taiwanese living abroad. The only reason for having a Taiwanese citizenship would be if we wanted to use their free healthcare, but we already have Canada for that. I could probably also regain my Chinese citizenship by jumping through some hoops, but again, why would I?
Having a Canadian citizenship definitely affects our FIRE goals, because it makes me less concerned about the state of healthcare in the U.S. If everything goes to hell, we can always move back to Canada.
Basically, having more citizenships gives you more options, but some countries are not worth the trouble.