Historically, for every Method Soap or Seventh Generation, there are 50 other brands on retail store shelves that are just like the majority. Rigid bottles, boxes with inner bag liners inside, metal tins, glass jars, etc. We call this The Sea of the SameTM and it's not letting up. We believe brands are still doing things this way for a few reasons.
There is a fear of changing and a fear of failure. If a lesser-known brand of baby food is making 5 percent margin on Target store shelves and they change their recognizable packaging, they could become lost completely on a store shelf. The meager 5 percent profit they are making now could become 3 percent, or worse. If they change their packaging and it doesn't work as hoped, or consumers don't like it, poof, they are bounced completely from Target.
Another reason is companies are not well versed in different types of packaging styles and materials. Their packaging distributor emphasizes and presents options in whatever his or her company specializes in (that could be corrugated or plastic or glass), and that's most likely as advanced as you'll get.
They don't know where to turn for new ideas or trends that have been used in other countries and industries that could be used successfully for their product. Finally, they just don't have the time or energy to consider other packaging options. It "could" require new equipment, or some capital expenditure, or some unknown factor they just don't want to face. Subsequently, they stay the same as every other competitor, and eventually they'll drift off into the sunset as obsolete products that "used" to be sold.