I'm sure he had a reason, pretty clearly every divergence from the book was carefully thought out, but it doesn't seem necessary and it makes Gimli look the fool, especially when he's babbling about hospitality when we can see bodies in the moonlight on the floor. And while Tolkien does use Gimli for comic relief occasionally, he's not stupid. If they had deleted the Balin story I could have understood it, but they did the whole sequence at his tomb and even reading part of the Book of Mazarbul; it seems that having him talk about Moria and his hope that his cousin will still be there would have only have increased the emotional impact of finding the tomb and book.
But still, two small nits among so much greatness. I think I'll have to see it at least one more time -- different things stood out for me this time and I caught many more details. I was less distracted by Legolas this time, and therefore caught more of the others in battle -- I still haven't caught Graydon's knee-kicking, but I saw more of the fighting styles he mentioned, Boromir's strength catching an orc blow with one hand, Aragon's constant movement, Gimli throwing axes.
And I loved Aragorn and especially Boromir even more this time. Having reread the book, I am ever more impressed with what they do in the movie. In the book, it's clear that Boromir is a great warrior and a proud man, but it's not at all clear he's a _good_ man, and thus the power of his temptation and the tragedy of his death is considerably muted. In the movie it's clear he is a good man, one who has been fighting all his life and watching ground lost every battle; one who knows his homeland is doomed without a miracle. I think to some degree PJ drew on Faramir his brother's characterization to develop this take; Faramir is the more reflective of the two and tells Frodo pretty much that when they meet in Ithilien. I'm wondering if this is a sign that the Ithilien sequence got cut; it's a pretty obvious candidate for being chopped in Two Towers, as the Barrow-downs sequence was in Fellowship.
And Amon Hen! Everything about it! From Boromir's childlike 'Frodo' as he wakes from his madness and realizes what he has done, to Aragorn's face as he turns to face the oncoming orcs, every inch the uncrowned King of Arnor and Gondor; from Merry and Pippin's luring of the orcs from Frodo, to Boromir's struggling again and again to rise, and fighting even from his knees when he can no longer stand. Legolas' fast-as-breath shooting; the mix of horror and dreamlike peace as the Uruk-hai captain leisurely draws his bow to finish off the kneeling Boromir; Sam's sturdy determination as he wades into the river he cannot swim to follow Frodo. Aragorn and Boromir's final words together, and the gentleness with which Aragorn kisses his forehead.
There's a lot of Boromir in that, but it's only just because Sean Bean owns that section of the movie. With timeshare rights for Viggo Mortenson.