Trust - increased by design
Allow for users to develop systems heuristics (ease of use) via design patterns while at the same time facilitate a detailed understanding to those who value the 'intelligent' technology used. (See Section 19.4.2. - Design for Human Error; Section 19.4.3. - Algorithmic transparency; and Section 19.4.4. - Progressive disclosure for further information.)
To avoid (a) that the user does not trust the outcome, and will act counter to the design, causing at best inefficiencies and at worst serious harms, or (b) that -trusting an application will do what we think it will do- an user can confirm their trust is justified.