We need the ability to pre-populate App questions with a default value. This not only gives the user an example of what type of data string the App is looking for, but also may avoid the user from having to do anything if the default folder or file is already correct.
This would also allow for quick App testing since we can just accept the defaults and not have to load up a yxwv file every single time.
ArcPy/Python, ESRI Modelbuilder, PyQGIS can all do this (heck, even MapBasic can do it!) - there's no doubt it's more convenient for the designer and end user.