http://www.straitstimes.com/singapore/education/moe-no-penalty-for-using-singlish-appropriately
It showed dialects or slangs which has longer history can be included in an official language.
In Japan during Meiji period, those who spoke Ryukyuan language, dialect in Okinawa, were punished and had to wear "Dialect card". Education like this made variety of dialects endangered or extincted.
So, even when a dialect you speak seems to be unsophisticated, do not hesitate to speak. Your courage to speak dialects can preserve history or culture.