The "happy endings, fairness, justice, heroes, villains, turnabouts, karma" JoshTriplett lists are the narrative projections which make life feel valuable in spite of life's trending towards wavering extremes of boredom and suffering.
The OP's argument coincides with the Buddhist and Taoist positions, who prescribe a lack of attachment to all mental constructs -- be that family, culture, love, hate, beauty, honor, good, evil, progress, and so on.
I get the logic behind it, it's an attempt to reduce life to the unassailably true. However, I think that sort of detached reductionism invariably leads to the view of the universe as a meaningless expanse of material, with an ordered procession of predestined material actions and reactions.
Is the meaningless material universe the true universe? Perhaps, but life feels like much more than that.
I prefer the ancient Hindu philosophical counterpart. They also believed, as the Buddhists and Taoists do, that at the most fundamental level it's all meaningless, but that by some miracle the meaningful emerges from the meaningless by way of our experience of it. The mind gives reality to the unreal, and that's a good thing.
Sure, the narrative we project onto the world may be fiction, but without it the material universe is a blank book. If life be fiction, give me fiction.