Ah, think I have an answer.
I'm willing to speculate that the people whjo didn't like the Kelvin sequence ar not parents. Not that you have to be a parent to like it, there are other beats in there too, but the whole parental thing could very well turn some people aside.
no, that's not it. otherwise I wouldn't be moved. I am not a parent.
I think it's about loss. deep, unutterable loss. if you've experienced it or at least have come close to it, you feel this scene more deeply than do the ones who haven't.
it's very important that we don't judge each other in terms of how we all feel toward this scene. we will all feel loss in our lives, at some point. some already have (like yours truly), some haven't... yet.
the scene is not about nobility or even sacrifice, really. it's about pain, unmitigated pain. something you can't do anything about. something that makes you cringe a bit inside to even think of facing. in the end, it's all up to our individual experiences in how we digest a scene like this.