You ask an excellent question.
But FSU has a great tradition of producing skill players and defensive players that succeed in the NFL. Anquan Boldin went to the same high school as Johnson....so he's a bit of an idol for boys growing up near Pahokee.
Also, FSU has a reputation of being a little less demanding regarding academic standards and extracurricular shenanigans. That scenario is appealing for quite a few recruits.
Plus, there is still some halo left from the '90's when FSU was a quasi-dynasty.