For good or bad Diki, Yamaha arranger players are attracted to Yamaha because of the many available translations and user styles for Yamaha and they feel those styles are sufficient for their needs.

And, as much as we like to think styles drive persons to get a new arranger, let us not discount the fact that persons buy a new arranger just to have something new.
Also, some persons buy a new keyboard for a combination of things. For example, some one who has the T3 of XS would upgrade to the T4 or XF for the styles yes but also for the improved sounds, additional hardware features (flash memory XLR mic input) and some OS features that they find they would like.