Through my experiences once someone passes away you should let go all the problems that you had with them, you don't have to say nice things but respect those who left. You wouldn't someone pissing on your grave right?

Its generally out of respect and a desire to remember the positive qualities about that person now that he/she is no longer here.

Out of respect for the family. He or she could have been a scumbag,but there was someone that did care for them. Even Hitler had a family right?

They're afraid of them coming back to take revenge.

Respect for the dead. Which is not always as universal as it could be. 1) "Jewish tradition places great importance on the "Levaya," the act of accompanying the dead body to the grave. Rashi presents an interesting rationale for this practice, declaring it beyond simply showing respect for the deceased. Rashi writes that inasmuch as one who is kind to the poor is looked upon as being a partner with the Almighty, it follows that someone who shows kindness to the dead (who are "poorer" than any living person), will certainly have gained this relationship with God. At Jacob's funeral, the eulogy given was described as being "great and heavy." The commentaries explain that the eulogy "weighed heavy" on the hearts of the mourners. In fact, Judaism says the essential purpose of a eulogy is to move people to a greater appreciation of the deceased, and deepen their recognition for what they once had - and have now lost. "Shiva," the seven-day period of mourning following a relative's burial, was instituted at this time by Jacob's family. Common sense (and modern psychology) supports this notion of devoting seven days to deep mourning after a great personal loss. Surprisingly, however, Jewish tradition does not see the mourners as the sole beneficiaries of the Shiva period. Instead, the Talmud explains how the soul of the deceased hovers over the body for seven days, and the specter of people mourning over the body that the soul formerly inhabited helps to ease the soul's pain." Source and further information: http://www.aish.com/tp/b/app/48944071.html 2) "Human burial practices are the manifestation of the human desire to demonstrate "respect for the dead", and to prevent the possibilities of revenants harming the living. Cultures vary in their mode of respect. Among the reasons for this are: - Respect for the physical remains. If left lying on top of the ground, scavengers may eat the corpse, considered disrespectful to the deceased in many (but not all) cultures. In Tibet, Sky burials return the remains to the cycle of life and acknowledge the body as "food," a core tenet of some Buddhist practices. - Burial can be seen as an attempt to bring closure to the deceased's family and friends. Psychologists in some Western Judeo-Christian quarters, as well as the US funeral industry, claim that by interring a body away from plain view, the pain of losing a loved one can be lessened. - Many cultures believe in an afterlife. Burial is sometimes believed to be a necessary step for an individual to reach the afterlife. - Many religions prescribe a particular way to live, which includes customs relating to disposal of the dead." Source and further information: http://en.wikipedia.org/wiki/Burial 3) "In late April (or was it early May) of 1999, I went to the memorial service for the Columbine victims. As I walked to the site of the service, which was attended by then VP Al Gore, Colorado Gov. Bill Owens, and singer Amy Grant, I saw a sight that would shock even the most desensitized amongst us. "GOD HATES FAGS" "MATT SHEPARD IS BURNING IN HELL!" "FAG = SIN" "THANK GOD FOR AIDS" ad nauseum. Those homophobic right wing christian nuts were picketing a memorial service for 12 slain children and a slain teacher! After the desire to beat those jerks to death with their own signs passed, I had a mental image of Jesus turning over in his grave so fast it would reverse Earth's rotation like in the Superman movie." Source and further information: http://www.voicesofunreason.com/essays/respectforthedead

Its more decent to remember the good, than admit the guy was a cheap ole bastard that never could say many kind things to others. ;) jk Its for the family sake as well, and for yourself. One might need to know a kind word or two would be possible at our own passings. POINTS!