"2. Why has this pistol not gained more popularity?"
I don't know, I've been doing my part recently to promote it.
It's only been 3 weeks, but I really like my FNP-45 USG (the model with a safety) and it is definitely an accurate pistol. The more I shoot it, the more I think it's just the right size for my hands. Everything else is starting to feel undersized, even the 1911s and especially the Rohrbaugh.
I think I'll buy some night sights when they become available for the 45.
FWIW, the free holster/mag pouch giveaway only included the 9 and 40.
John