One of the most basic assumptions that an audience makes is that the person who created the entertainment they’re about to enjoy is going to treat them fairly. They assume that everything they witness has a point, and is necessary to the story. Audiences are prepared to accept small exceptions to this rule – writers are allowed a few red herrings and MacGuffins – but break it in a major way and they’re going to feel cheated...
The secret storytelling truth we must mainline:
Be aware of the contract between you and your audience. Everything that happens must happen for a reason, and the more of a big deal you make of an event, the bigger the pay off must be.
Source: LitReactor (Spoiler Alert for True Detective: Season Two)
I suggest every author who sees this read the entire article.