I could only see this being useful if animals would eat from the hay bales when we put them on the ground. Make each hay bale require 64 wheat or something, and have it deplete as the animals eat it.
or you make a tie for it, and then you have to make a base block (like a chest) with in the crafting box completely, then you craft them together making the bale, then you will be able to add wheat to the block and you can then check on it and the animals will feed on it
Hm I like it. Maybe animals could stayed attracted around hay bales. Or maybe even enabling animal spawning around it, or animals could breed themselves automatically. Of course that would need balance, especially for SMP to avoid any spamming.
I'm sure there's plenty of ideas to find, simple and effective.
I think they point more towards Jebs idea of horses in the game, however It very well could be a red herring and hasnt been confirmed yet.Also I think It would be nice for decoration, but maybe a 2x2 square of wheat rather than a 3x3. If you think about it thats 9 wheat per block. Then time 9 by the roofing you need to cover your barn or whatever. Adds up