Yeah, I dunno that it's just convenience. My dog really seems to turn her nose up at "stale" kibble. I know it's just sitting around in a bag anyway, but I think it gets more stale once the bags are open. Just 2 cents. I know it's mainly convenience and penalizing people who can't afford to have much storage where they live.
Have you tried different food? As they age, some dogs just stop liking what they've eaten for years. That's exactly where I buy from. SPORTMiX Wholesomes Chicken Meal & Rice Formula Adult Dry Dog Food, 40-lb bag, two bags every 10 weeks, free shipping. Better quality than Purina One, which makes my mastiff stink for some reason.