Why do nice cereals only come in small boxes?

What's the deal with breakfast cereals? I was just replenishing my supplies last night at my local (not very) super-market. It bothers me that all the best cereals come in ridiculously small boxes. If I wanted a cheap and nasty cereal that's 90% sugar, I can get a box the size of a small house. If I want something like "maple pecan crunch" or Alpen, though, it's a different story. We are being conditioned to eat bad cereals! I had a bowl of Alpen this morning which was very nice but I couldn't help noticing that the box was half empty (or half full?) after ONE BOWLFUL!