Unlike shift work and gate guarding - its just a bit difficult to pop down the NAAFI to grab a butty while you are at 30K ft on a 10 hour sortie!! Therefore aircrew will need feeding! As for only getting food when flying over meal times - these are also difficult to manage what with different time zones and unsocial working hours etc to consider. Sounds like a good few flight safety reports coming up caused by low blood sugar!
Also sounds a cost saving exercise!!