If you just want to show off what you have, but don't want to let people take any. For example, you can fill a chest with various items that you are auctioning off. Everyone can see them and know what they are bidding on, without being able to take them. Other uses may be to publicly disclose inventory levels in a shop or show off how many rare items you have without building a giant display of item frames.
Ive seen stuff like this using the Lockette plugin. It was called a "Donation" chest. The chest was accessible by anyone and items could be added to the chest but not removed by anyone but the owner. +1 for display chests
A display chest would be good for shops too. So that customers can see what is left inside and determine how much they want from it or how much is left and available to take. That would be cool if a chest could be a shop and a display for this kind of concept. So, I vote yes.
