There is nothing wrong with not telling anyone anything... but in that case almost everything you do should yield SOMETHING. So through trial and error you find the recipe for a crummy breastplate.
Working off that (because the recipes make sense: increase the quality of the ingredients and the quality of the final product goes up) you then use better metals and make a normal breastplate. Then use some Mithril and really get crackin'.
I would be all for having something like that, but the world would have to have a vast assortment of misc. crafted items that essentially are failures but give the player evidence to look in the right direction:
Uses pine wood to make a breastplate:
You get Pine Breastplate:
Descript:
This piece of pine resembles breastplate, however the wood is flimsy and wouldn't hold up in battle.
The description gives you a hint at how to do better: Get better materials. Maybe next time this druid crafter will try ironwood or some other harder wood.
That would be an excellent thing to do... but it would be a TON of work
I'll also say: My enchanter would like to publish books detailing crafting recipes (via a Use, not examine, as then they wouldn't have to buy the thing