I think pre-ordering is fine (although I agree with others that I won't always want to as I don't always know in advance what I fancy). However, what I'd propose is to make pre-ordering better by using the reduced waste that ensues and saved costs for airlines by expanding the pre-ordered options as opposed to limiting pre-ordering to the 'normal' menu (ie make it 'book the cook' instead of 'AA style'). By expanding options if pre-ordered, you'd then encourage more people to pre-order as they'd know they will only have - say - 4 options to choose from onboard as opposed to 10 if pre-ordered.