Answer:
Because after 1763, England began to increase the control under the Thirteen Colonies, creating laws and taxes that benefit only itself, avoiding the self-development of the colonies. The republican ideas became common and spread over the country because the founding fathers did not want to create the same government in America. In a nutshell, they were against a monarchy, and all that this kind of government represents.
Explanation:
After the British victory in the Seven Years' War, to recover the finances, England began to create taxes and laws over its most profitable colonies in America. Until that moment, the Thirteen Colonies saw liberty that was not common in the American colonies at that time (especially if we consider the Iberian colonies). Then, England began to create terrible taxations, Proclamation line, Stamp Act, Sugar Act, Tea Act, Townshend Duties, all these laws to enforce and control the colonies displeased the settlers a lot, creating the feeling of republicanism and independence.