In my vMix scripts (https://github.com/rse/vmix-scripts/) I've multiple times wished it would be possible that the user can attach an arbitrary string to a vMix input (e.g. under "General") and any input layers (e.g. as an extra column on "Layers") which is then also available on the API. This way one could more flexibly script vMix.

Because currently the only ways are adding something to the input title or place a disabled Title input on a layer. Both approaches are nasty: the extended title looks strange in the GUI and extra title input is a overkill. So, just provide text fields where the user can enter arbitrary textual information which a script can read via the API.

In case scripting is not the goal, those "Custom User Information" fields would be also great for being able to place arbitrary comments onto the inputs and their layers. I've multiple times wished I could document the purpose of an input or especially the reason for a layer.