Why don't you use them? Is it because your pantry is well-organized already, and you don't need the extra space? Is it because they are behind the door, and you aren't used to looking for things in that location? What were your plans for them when you bought them?

I have two similar racks for our pantry doors. Mine hold an assortment of things like canned goods, baking items (baking powder/soda, vanilla extract, food coloring, chocolate chips, brown sugar), smaller boxed goods (corn muffin mix, mac & cheese), oils and bulk seasoning. By moving my baking items, bulk seasoning and oils out of my spice cabinet, I've freed up lots of space in my spice cabinet and it's so much easier to find things. Love my behind the door racks!

I haven't been using them because I do have a lot of space in the actual pantry closets and I also haven't quite identified which type of things might be better off there. I was concerned that putting cans or bottles on the doors would be too heavy, so for example, I didn't want to put bottles of oils or vinegar on the door.

Too bad they didn't give you a load rating - though I would expect those brackets are plenty sturdy. Unless they feel flimsy in person, I wouldn't hesitate to load them up.