TL;DR: Water physics without water look. Give more possibilities to developers.
I was thinking recently about making boats in terrain-based games. Water physics are excellent, but not so much for boats if you’d like space inside them. With an InvisibleWater terrain material it’d be possible to script the water to be invisible inside the boat without affecting physics. This would also allow for water physics to be used in a variety of situations but with custom visuals.
Water rendering too laggy? Use InvisibleWater and a custom repeating water texture.
Need space inside boats? Use InvisibleWater and HumanoidStateTransition control.
Need custom water blocks? Use InvisibleWater shaped to the blocks.
Overall, the idea is to partially separate water physics from water rendering, which brings more possibilities to developers.
I’d just like to be able to give water physics to any object/material.
edit : I mean, without having to put invisible smooth-terrain water around it. It’d be easier to have a property or an object you put into things that makes them act like smooth-terrain water.