The earlier days of republic law in the earlier days of the US had, perhaps, 'simpler" worries. Rather than gun violence, abortion, and sexual assault issues, the earlier republics were more concerned with revolution and civil war.
Nowadays, modern republics are more concerned with modern issues such as racial inequality, gay/trans rights, and the economy more than anything. The two-party system has ultimately developed specific issues important to them and their stances on those issues, so someone who wants to be elected to office must appeal to the most issues of their party that they possibly can in order to be seen in court of American Public Opinion as "in the constituents' best interest."
