Darque

technically speaking what they are wanting to achieve is the ability to change the clarity of the water fog based on if you have an equipped item and/or respiration enchantment. not necessarily changing the rendering if doesn't have to be a change that affects lighting or render distance. just to be able to change how the underwater fog works.

you may think its not "Needed" but technically forge is not needed for making a mod some other bloke could vary well make there own api for there mod. what there saying is that the mod may not have direct use for you or others but give people an ability to use it and people will probably use it. For example: a person is making a race mod to add races like dwarves elves and so on. In caves the mod could add fog then some races with the hook would be able to see thru the fog while others can't. as well as what Azaka7 is trying to do it would be nice to have the ability to change the fog clarity give them the means to do something and they will use it that's my opinion