I agree with you that I could use a LET statement to set it to null but from an application/product standpoint the variable should be deleted from the application if it is no longer being referenced.
Without the 'Variable Overview Screen', you as a developer have no way of knowing what variables may or may not have been created. This caused an issue for me trying to debug some complicated set analysis over a large population of data. I also had an issue where I had a variable originally tied to a filter object and upon adding a variable with the same name I was surprised to see it automatically tied back to that object. Since I knew that I had originally added a variable by that name, I quickly figured out what was happening. If it was another developer that was making changes to the application, how would they have ever known that this variable once existed?
I'm not trying to be negative but I do think that this is an issue. A 'Variable Overview Screen' needs to be added or the variable needs to be deleted when no longer referenced (or deleted from the script).
Thanks for your input. Just wanted to verify that I wasn't the only one this happened to.