Considering that audio styles are "the way they are" once they have been recorded, whereas for midi styles every single note of every instrument involved can be eliminated or recomposed - I think it is probably quite expensive for the manufacturer to be up-to-date regarding the newest pop music with audio styles. If some new dance or rhythm has been invented, all a manufacturer had to do up to now was reprogram the midi styles with the samples already existing, maybe add a certain drum sample. With audio styles, real musicians have to be hired again for a sampling session.