I don't think I saw this response previously, but it is my understanding that it is all about shelf presence. The bigger the package the better the chance the consumer will spot it first. Someone talked about cereal boxes, but all boxes fall into this category. Anyone ever buy computer software or games off the shelf (back in the good old days) just to discover that all that gigantic box had inside it was a floppy disk or CD? Vendors in grocery stores fight over shelf space, so why not in the pharmacy as well?