The cases where `_user` is required, and a user data / ID view is used, far outnumber the cases where it is optional. When `_user` is optional, it seems to usually be used only in certain scenarios (ie. if an action requires certain permissions). I think it makes more sense to have the user data / ID views require that `_user` be present by default. Perhaps adding a parameter to `userDataView` and `userIDView` to mark `_user` as being optional would work, though.