While I admit that 15p is a strange addition, I guess that it's up to potential buyers to really inform themselves before they click that "BUY" button. TO buy just because "4k" is typed on the box, may be a frequent behaviour, but that doesn't make it better. A simple online review should be enough to find out that 4k isn't really useable that way.
Except if Fuji decides to magically unlock 24p in a later "Kaizen firmware update" (which is the name of the game they play).