I mentioned in another thread, there are some otherwise major saintly names that have never been used, including several apostles and founders:
No Thomas, either, or Timothy; no Damian or Cosimas(Cosmo), nor Augustine, Jerome or Polycarp, apparently.
And until now, no Francis.
I suspect partly because for most of the flock, “Francis” calls up one specific saint: Francis of Assisi. And to imply that this is who you are going to model yourself after… is to task yourself mightily.