I apologize for the incoherent and incomplete post of yesterday.
What I meant to address was, the benefits of withholding for both plot advancement and reader investment. The way this works is the same way enjambment works in poetry. In a poem, when a poet ends a line in such a way that the audience overwhelmingly anticipates the word or idea on the next line, but then is surprised by a subversion of that assumption, the poet has succeeded in a glorious manipulation that actually results in buy in.
Enjambment literally means "to straddle." It's an incomplete thought that continues after the reader has aligned herself with the pause and has made some assumptions about its trajectory.
Take for example this passage from Milton's Paradise Lost:
… now conscience wakes despair
That slumbered, wakes the bitter memory
Of what he was, what is, and what must be
Worse; of worse deeds worse sufferings must ensue.
Between lines three and four is the sort of enjambment that wakes up a reader. It's the unresolved becoming the surprise, full of gravity and emotion. It's about subverting expectation and producing the lift we call art.