The problem with this is that one person's 'must have' is another's 'waste of space'.
We did take an over-door shoe hanger once but didn't really need it, so haven't bothered since. We have never felt the lack of magnetic hooks etc either. However, I do take a small tube of laundry detergent whilst other people are horrified at the thought of washing clothes on holiday.
My essentials are medications, device chargers, travel documents and credit card/s. However, I don't travel light (we are within an hour of our nearest departure port) and tend to think 'put them both in' when wondering whether I should take A or B top/dress/shoes etc!