Aesthetics, creative license, preference, following the theme, why should there be a reason? I thought it was cool.

Exactly. Most people don't get it, apparently. The ending is amazing as it is!

Cooper's character gave me strong gamer/reactioner (is that even a word?) vibes, kind of like PewDiePie. You know, they always keep talking, commenting on what they see and making jokes about it. Maybe portraying his character that way was done on purpose, the actor even looked like him but I might be reaching here.

But why would her mother have developed Alzheimer's? That wouldn't make sense at all. Isn't it far more terrifying that he died while his mom was calling him and that, at the same time, in a matter of 0.4 seconds, he died while calling out for her? I loved the ending as it is to be honest, it's brilliant.