Scientific Topic on Wikipedia originated from a Scientific Article with Low Citations
Wikipedia is a volunteer encyclopedia. People write whatever they want to write about. Someone found Fubini–Study metric interesting enough to write a big article on it (you can look through the article's history to see who they are). This doesn't mean the subject is very notable, only that it meets Wikipedia's so-called "general notability guideline". Therefore there's no reason to expect that the scientific articles that initiated the Fubini-Study metric to have a lot of citations.

As an illustrative comparison: the relatively obscure Bowling Green State University has a much more comprehensive article than the more highly ranked, bigger, and richer University of Tokyo. This doesn't mean that Bowling Green State University is somehow more notable than the University of Tokyo; more likely it means that among Wikipedia editors there are more BGSU alumni than UTokyo alumni - which shouldn't be surprising, since these Wikipedia articles are written in English. Compare the same articles in Japanese.