Real people and real events are inherently more interesting, complex and extraordinary than fictional characters or scripted plots could ever hope to be. Real people need no help from actors to tell their story and real events need no embellishment from dramatizations to move us.
Objectivity is a sham.
A documentary should wear its heart on its sleeve, not hide behind a facade of neutrality. Introspection is over done. So is reverence. Documentary should seek broad themes and archetypes in the experience of common folk, not insular filmmaker self-reflection or celebrity homage. Humor and satire are underappreciated, underrated and under-used.