At present, the only functionality of the Smithing Table is that it acts as a Villager toolsmiths job site block.
I think that the block ought to be usable by the player, specifically, to act as a complement to the anvil.
When items are repeatedly worked on the anvil, the cost, in player levels, goes up, due to something called the "prior work penalty" increasing.
This idea is to give the Smithing Table the ability to reduce the "prior work penalty".
The player opens the block's GUI, puts in any item with a Prior Work Penalty (PWP) greater than zero, and some furnace fuel, then selects how much he wants the block to reduce the item's PWP, then clicks on a start button.
For each unit of PWP that the player has chosen to remove from the item, the block takes from the player a matching number of Experience Levels.
The block stores inside itself however many Experience Points it had to take to produce that XP Level reduction.
The block then heats (tempers?) the item, burning fuel and experience points, with the Experience Points inside itself going down by one per game tick.
When the XP in the block is fully consumed, the item is moved from the input slot to the output slot.
Fuel, input, and output can all be automated like a furnace, but starting the operation requires player interaction.
Similarly to enchanting, there might be a minimum player level.
The amount of time needed for a level 30 player to reduce an item's Prior Work Penalty by one is 107 ticks, or just over 5 seconds... which is, hopefully, neither too laborious, nor too overpowered.
First, I'd like to say that I like that this suggestion attempts to give a nearly useless block a use at the same time as solving another problem. There are a lot of suggestions that try to make up uses in order to fix things, and that's not always bad, but it's often better to kill two birds with one stone.
However, I don't really see Prior Work Penalty as a problem to be solved. I also think that something as generic as a "Smithing Table" should have a less niche use.