Better teaching: Objectives on the board

Why not start each class with a provocative question (on today's topic) to promote engagement and dialog?
Arguments for    

WHY are learning objectives so important? (Thy're not just for inspections)

Link John Hattie on YouTube. 5 mins
Explicit Instruction. Class begins with students reading out the class objectives YouTube video. 7 mins
Against against    
Stop writing the objectives on the board.
Excellent, provocative introduction with over 50 comments.
Reasons for and against. From
7 reasons: Why we need to kill boring ‘learning objectives’! Link An interesting critique of learning objectives