I've had both, a fbp diesel motor home and several fifth wheels without it. I know it is an available option on the Pinnacle but when looking for our model on the on line for sale sites I never saw a single one with fbp. I guess the extra cost would not make them competitive with other brands so dealers probably avoid it for stock units. I usually wax mine once a year and I've not noticed any difference in keeping an unpainted vs painted shiny.
What might make a difference is the vinyl decals on an unpainted version which can have a tendency to deteriorate if it lives outdoors full time. Ours stays indoors except when on the road so this has never been an issue for us. I know the front and rear caps on the Pinnacles are painted so it's already part way there.
2020 F350 Platinum, srw, lbcc, 4X4, 6.7 diesel, 12,400 GVWR
2020 Pinnacle 32RLTS