Well, Trujillo made it mandatory...
He called it: 'Musica de Papa Dios' (God the Father's Music)
"Trujillo clothe himself in the merengue, promoting it as a national (read political) symbol. Top merengue bands were renamed after him, propaganda songs were written and performed, and his brother Petán was allowed to run a major radio station that broadcast live merengue music. La Voz Dominicana
as it was called, played a great role in consolidating national acceptance of merengue cibaeño.
Even the upper classes were not immune because they were compelled to play merengue cibaeño at all formal social occasions. Perhaps President Trujillo delighted in this: he was an avid merengue dancer although he was not originally of the Cibao region, and his early attempts to fraternise with the elite while he was of junior rank had been spurned."http://www.salsa-merengue.co.uk/revealit/histmer/prologue.html