Hey there, LastTech-
There's a really good reason we don't automatically delete what you're using - if you have two files in the same directory, chances are you're sharing the images directory. If you make it so that you delete everything in the images directory, you could be deleting something that another project (or another HTML file) is dependent on. It's very difficult for us to determine what is used in other projects, so we just leave the images/ directory alone.
Thanks,
-Elaine