I appreciate all of those points, most of which also apply to the "full meals" that some airlines provide. Maybe the flight duration is the key to getting it right.
On Air Portugal Faro to Lisbon (very short) we had an offer of a choc-ice or a biscuit-pack - suits me fine. On a Monarch Gatwick to Thessaloniki (4hrs?) we had the usual tray of bits and pieces. Judging by the clear-up period a lot of people seemed to reject about 50% of that food.
My personal preferences would be: <2hrs Not bothered at all; >2hrs<3hrs Snack/sandwich availability; longer flights, the current set-up seems about right. Unfortunately a high level of waste is common in the food business everywhere. Letting customers down completely (no food when expected) is obviously a big problem, whereas not having their favourite filling is not so bad. People with special dietary needs are probably used to catering for these travel times. It's a bit of a minefield really, isn't it? Knowing what to expect is important, which is why I asked in the first place.