Languages change for extrinsic (heteronomous) reasons as well as intrinsic (autonomous) ones. A typical extrinsic cause of linguistic change is prestige. While all speakers generally are impelled to speak like their fellows, the spur to imitate the speech of others is particularly potent when prestige is involved.
This situation is true of institutionally regulated speech as well. Thus, in the recent past, speakers of British English (as heard, for instance on the BBC World Service) have largely converted to using the word sports in the plural rather than the traditional British English singular sport. This change can only be reckoned as resulting from the influence of American English (where sports is de rigueur), whose prestige has grown to such an extent that even speakers from the mother country must now bow to its status as the world language and change their idiolect accordingly. Autres temps, autres mœurs.