why harry potter movie didnt let the story on how harry's parent died?

Well they showed HP's mother bein killed by da dark lord... But the story s told by Hagrid to Harry in the first part...

That is a good question. The movies don't tell near as much as the books due and knowing how his parents did is really important. That should of been included in the movie also.Like the first one maybe.

i think its becoz harry potter movies are intended for the whole family which means even kids of very young age can watch it and uts not advisable and good for them to see parents being killed violently, its all about "kids shouldn't see violence" thing. as for the reason why harry's parents being killed, they tried to stop Voldemort from killing harry and he killed them first to get to harry. Voldemort wanted to kill Harry and the other child borne on that year becoz there was a prophesy on that year a child of great power will be born and it was said that neither of them(Voldemort and the the child, who Voldemort thought is Harry) can live as the other one is alive, meaning only one of them should live on that generation. (i read about it on book 5 Harry Potter and the Order of Phoenix) :p