I'd say that knowing the inevitable comclusion would have the positive benefit of cherishing every moment precisely for knowing it's end. It opens up he inevitable thought of our own deaths and those of the people we love and that because death is a very hard thing to stare in the eye we then miss a similar cogniscance to enjoy what we have when we have it. We don't have Louise's advantage in a way. We don't have those "memories"/ images of the future to keep us powered up to cherish our families.
Again I'm enthused that the film can springboard towards these thoughts. Thankfully it never slammed the door on a more philosophical process. Nice afterimages.
I just didn't care at all for these characters either, so that has a lot to do with it.
This is perplexing merely for the film being so much about Adams' Louise that to term it "these characters" misses the point in itself. I feel that by this point Adams primacy as an actor has gone beyond doubt. You could contend with my feeling that she is the best actor working anywhere, confirmed by this film and what she is asked to do; little else I feel.
Renner and Whitaker aren't engaging ? fine. They are in the film but it isn't their film. It's Adams'. I know she interpreted a lot of what Villeneuve was describing to her into facial reaction. That's why it's especially wonderful that she was acting to two tennis balls whilst the director explains what he wanted to convey but Adams is doing the hard work here.