FUCK, I just wrote out a long reply and accidentally deleted it. Ugh.
Okay, short version of what I was saying: I know why Oda does it, but it doesn't work for me. In fact, it has the direct opposite effect. I don't have many universal rules for storytelling, but one that seems to yet be disproven is the element of believably, or immersion. When I'm seeing a story unfold, it doesn't matter what medium it is, I need to be immersed into whats happening to believe it, which is the only way to emotionally connect to the story for me. When I'm reading a book, I am not aware I am looking on words on a page, I'm witnessing it in my minds eye. When I'm reading comics or manga, it is real to me in my mind as it unfolds.
Ace's death was an impeccably well done scene, until the moment Luffy's face deformed. His row of teeth somehow became all one giant tooth on the each jaw, hugely enlarged, and his pupils gone with his tongue suddenly being larger than his palm width would be. It's simply not possible within the context of his universe to make a face like that, even with his rubber powers.
My immersion is broken like shattered glass. I'm not witnessing the death of someone dear to Luffy. I'm looking at a manga, a book. I'm looking at patterns of ink on white paper that are designed to represent human beings, but aren't. I cannot believe in this scene as it is depicted. Any emotional engagement I have is now gone. I cannot believe in these characters as people, so I have no empathy for them. If anything, it makes me laugh how stupid it looks. I shouldn't be laughing at this scene, but hilarity is the only emotion it can elicit from me, the very notion I am supposed to find this clownish display sad. Obviously, I am rather unique among people who read the manga, and for most of you, it doesn't break you out of the story. But for me, this scene was especially frustrating because Oda finally managed to get me engaged, and he ruins it with his stupid ass deformation faces. This isn't raw emotion. All it does is emphasize how artificial it all is.