Here's My idea: Why not make tool durability use time instead of uses. For instance if you had a diamond pick it could mine as many block, inside an hour of use (time mining). Now tough blocks (such as obsidian) would ware down the tool faster because it takes more time to mine it. Additionally if you use the wrong tool on an item it would take 3 times as longer (pick on dirt) This would make it more important to use the right tool. As it stands now using the wrong tool uses up two uses instead of one, not a big difference.
Cucumber
Remember, that was just an idea i had, doesn't mean it's perfect. I have to admit, the old system is a lot simpler.
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