Voice actor nailed that scene so well. I'd probably get a little moist even without the backstory.
Yeah, I love this game. I ended up watching a genocide run instead of playing it.
Parts that made me laugh: Tons.
Parts that made me catch something in my eye: Everything you mentioned and...
Everyone calling in to say goodbye to Mettaton. During the fight with Asgore: Telling him you don't want to fight causes him to breath heavy, or otherwise lose his composure. You can really tell he doesn't want to fight either, but he "must." Likewise, the final battle with Asriel is a tear jerker, though a more positive one.
I watched my friend play through a neutral game. It's nowhere near as good as a pacifist run, but it has some moments. Killing Undyne is an incredibly sad scene. He only left Papyrus alive, out of all the bosses, so he became the King. Sans tells Papyrus that Asgore, Undyne, Alphys, and Mettaton are all on vacation, which he seems to believe. He tries to keep spirits up, in his delightful Papyrus way, but confesses that it's been hard lately: Everyone seems to want to give up. Also, he really misses Undyne. She never answers his calls... (she's dead) and wishes she would at least send a post card.
Q__Q