I realy like that crates can be used for bulk sotorage, but when it comes to storrage of food they fall short. You can see Crocks freshness at a glance, same with items on a shelf, and when you open the storrage vessel you can inspect each item to see its freshness easily... on the other hand you need to take an item from the crate, then inspect the item, do some math (or put it in a storage vessel) since things you hold spoil faster in your hands, then put it back. All the items in the crate have the same freshness so could easily fit in the tool tip. Though i suspect there probably is a code reason this is not implemented yet, i hope this is something that could be implemented sometime in the future.
Also crates seem to have a wierd freshness calculation as it seems they use the first iserted items freshness for everything inserted after rather than averaging like in the inventory or a vessel.
Edit:
Another similar situation is that jugs also do not show spoilage of their contents. They also do not even show what they containon when on shelfs.