[The Saucepan Man]

If they had done the scene as it was in the book, I don't think the audience would have turned on Sam.

Actually, I find it quite easy to imagine people coming out of the cinema saying "I don't like how that Sam turned the cute Gollum dude against them". And that would have provided yet another bone of contention for Tolkien (book) fans, many of whom would no doubt be ranting about how Jackson "messed up" the scene (although, as I said, I think that it would have been very difficult to portray properly on screen).

I think they would just realise the hopelessness of the situation and feel sad for everyone concerned.

But that's the point. Jackson didn't want people feeling sad for Gollum in RotK. As director, that's how he chose to play it.

I think that it's always important to bear in mind in these discussions that the story told in the films is a different one from that told in the books, albeit based on it. Omitting this scene and adding in the lembas scene didn't make the films internally inconsistent (Frodo's mercy still has an important role to play) and it certainly didn't detract from them as far as I am concerned.