I generally eat all meals, especially in Business or First Class.
I know it sounds ridiculous to some people - possibly the OP included - but more often than not dining in Business and First Classes are an experience for me, not just a means of sustenance. So having the meal on board - even if there is lounge food before and/or after it - is nearly mandatory in that regard (and if it isn't any good, it will make for an interesting story afterwards).
I don't think the smell of food from the galley has ever put me off (and those who have met me, yes I may like food that much but I do have standards, too). Frankly most of the time it tends to smell the same; I guess more precisely, many of the meals themselves are tight foil wrapped so you can't really smell them until they are unwrapped (only mainly applicable in Business and First Classes). Bread / bakery is different because they are put in the oven uncovered, but even then unless they are taken to a fairly toasty level, it can be hard to smell them as well sometimes. So in all the smell from the galley tends to be much the same (or rather not too much different to anyone else's kitchen).
I've maybe only declined meals once or twice, but not because they were inedible (read: literally inedible; most airline meals at least taste good or acceptable if they don't look good). Main reason has been that I've skipped a meal to catch up on sleep. One time I asked a meal to be postponed (i.e. service was usually at the start of the flight, but I asked to sleep first and have it served before landing, request was granted). The meals served can be rather strange with respect to time, but in most cases I'll still eat what is given. The stomach doesn't seem to mind and the mind, well, you are travelling anyway so if it isn't messed up by now then why would your dietary habits do anything different.
Whilst some people may eat before (or after) being on board and not have a morsel on the plane, I usually bank on having something to eat on board in anticipation of not having to eat something either before or (more often) after the flight. For example, if I have rushed into a lounge before a flight to finalise some business (with full on-ground connectivity), I could be lucky to grab a drink or a snack and work at the same time, but eating a full meal without necessarily scoffing it down is awkward. Similarly, having eaten on board before landing, even if there is an arrivals facility or lounge in transit that I could rely on for extra (possibly better) sustenance, if I need to be in a position to "just go", I can do that, too.
Whilst airlines may enjoy the OP's idea from the point of view of saving money, I don't think it would be an overly popular idea at all with the majority, even if the quality of meals to many people is questionable at best.