That is because they did their own thing with DH part 2.

The book in my opinion is far more epic feeling for more than just Harry. When Hagrid is carrying Harry back Voldemort starts to mock the remaining wizards and witches about the boy who "lived". Neville really does defend Harry, but I don't remember if he cheeses it up with the heart metaphor. Voldemort goes over to Neville with Nagini (snake horcrux) following. The Sorting Hat is nearby, and Neville dodges toward it when he sees a gleam. He pulls the Sword of Gryffindor from the hat, and decapitates Nagini. None of this Ron and Hermoine fumbling around for a Basilisk tooth bullshit from the movie. Neville gets his time to shine, and to destroy a part of the soul of the man who had his parents cursed.

Everyone breaks into battle as Harry springs back into action. Ron's mum still calls Bellatrix a bitch and kills her after she attacks Ginny. Afterwards Harry, and Voldemort are dueling while both sides start to form a mob pit around them.

Harry mocks Voldemort and keeps calling him Tom, and saying he will see what he becomes if he doesn't ask for forgiveness and stop. It is actually the coolest bit of dialogue to me that they should have kept since Harry is getting a rise out of Voldemort, and is no longer afraid of him.

One more spell from each side. He doesn't turn into a million pieces of skin flakes, but collapses lifelessly to the floor like a normal fucking body.

I also feel like if they were going to do two bodies they could have done a better job about the Grinderwald side-story, and Abernath's sister instead of white washing Dumbledore as some flawless saint.