Confused about Quotations!!

[Bombadil]

I have this anger, this real anger! As I re-read the Lord of the Rings, I come across some quotes that Jackson picked for his movie. I don't kow why it annoys me so - but WHY does he have to change around every quote one or two words!!! Why couldn't he use the exact words of Tolkien? Were there copyright issues? I don't think so, considering he uses some lines dead on, in particular:

I will not say do not weep, for not all tears are an evil.

And I'm sure (or i hope) there are some more. Is he exercising poetic license? If anyone knows why please reply!

Another side question- perhaps better for discussion purposes: Why do you think PJ went into such detail in certain clips than others? You have clips like when Frodo is leaving the Shire, and there's so much detail skipped over - but for some reason Jackson made his clip for Smeagol and Deagol in the beginning of ROTK almost word for word with the description! You may now...discuss!