usefull cauldrons

on bedrock cauldrons have the capability to hold dyed water and potions which was used to dye clothes and to make tipped arrows respectively. These should be added to Java. Not only will it give more uses to cauldrons it can also allow for more creativity

In addition 

drip dying up to a stack of candles for personalized colors

washing away dye on non white items for recoloring possibilities (this would dye the previous clean water) or add that different colors can be used to create something (bed/chests/etc.) items with different colors will be default color or take on the color most used.