Option to negate an input instead of using a NOT-gate, like you can in most other programs. NOT gates make logic look messy very fast. This would be a neat feature.
It works by tapping on an input, and it will create a visual effect such as a dot, representing the negated input function. This means logic that is plugged in here will be negated (like it is being passed through a NOT gate) before entering the gadget.
I agree with KemwerSeth. NOT gates are there for a reason ^^
Also, if every wire could be negated, and most wires aren't anyway, it would only decrease performance or other things, because then there would be another information to store about every wire.
The NOT-gate allows you to quickly see if the output is being negated or not, instead of relying on a tiny dot that would very hard to read unless you are close to the microchip. This is a solved problem.