The government has banned books and made many things culturally unacceptable; Beatty, speaking to Montag as he tries to convince him that his culture is correct, explains part of the reasoning for eliminating funerals:
"Funerals are unhappy and pagan? Eliminate them, too. Five minutes after a person is dead he's on his way to... the Incinerators... Let's not quibble over individuals with memoriams. Forget them. Burn them all, burn everything."
(Bradbury, Fahrenheit 451, Google Books)
This is part of the government's social engineering project to control people and remove their individuality. Since the government has conditioned people to believe that their lives don't matter, the pomp and circumstance of funerals becomes unnecessary. Instead, people die and are cremated; their lives need no eulogizing or remembrance because everyone is just like everyone else. By destroying the memorial of a funeral, and the expectation that people will remember their dead friends and strive to be better, the government makes death a non-event. This allows firemen to have the power of government-sanctioned murder when they burn buildings, and no one bats an eye.