I didn't find it distracting at all that no one around him "seemed to care that he was aging backwards" as the social aspects of his condition were not what the movie was about, we don't know that people didn't find it exceedingly odd, Fincher chooses not to show us those parts of his life.
As for the "spitting in the face of the arrow of time", really? This movie is fiction, somewhat of a fantasy, so who cares if it doesn't play by real world rules. You want real life? We're living in it, movies are a way for us to experience things that are fantastic, things that could never happen and so we can say "what would I have done in that situation?" "what would my life have been like if that was me, would I have made the most of it?" and hopefully at the end we can take things from it and apply to our own lives and hopefully become better people. Yes, action movies and such are meant to entertain our eyes with explosions and dazzling effects but movies like this are meant to make you think, and it certainly has made me think. I do like some of Fincher's other films but this is his best without doubt.
I fail to see anything "brazen" abut the storytelling of the movie. I understand that not everyone likes the same thing but I have a feeling some people have completely missed the point the filmmakers were trying to make. One has to have some emotional maturity to understand the themes, men who are still children probably can't see things that deep. I wouldn't suggest that younger people watch this film as most of the themes are not intended for young people who've not experienced loss, love, tragedy. I hate to always bring up age in regards to love of film but it's a factor, no doubt in my mind. Young people see the world differently than older people, stands to reason they'd like different movies, oh and the research has pretty much proven it so for the young people here (and I know there are tons, too many IMO) don't get all uppity and mad at me for saying the truth.