Why did the Protestants place emphasis on the literacy of the laity?

In Protestantism, The Bible is the supreme authority for all religious matters-not the sacraments or the rules and interpretations of the Bible set down by a central authority figure such as the Roman Catholic Pope, for example.During the Protestant Reformation, when the Bible was widely published, Protestants were encouraged to read the bible directly for themselves.Thie produced a literate Protestant population, as the Roman Catholic Church theology at this time did not encourage people until a later time to read and interpret the Bible directly for themselves. Protestants are still guided by principals gleaned from the Bible rather than rules and ritual emenating from a church hierachy.