One of the reasons I can think of for WotC removing the 10th level crafting reduction is the overall changes to crafting.
14 an uncommon item takes 20 days and cost 500, an artificer takes 5 days and cost 250 gold.
24 an uncommon item takes 10 days and cost 200. it still takes longer if it is not part of your specialty.
I can see adding a blanket 1/2 time stacking with your specialty at 10th level.
In one of our games the dm made a magical item to let the artificer craft quicker so a short rest gave you a full days work and a full day gave you 5 days of work.