I have searched the forums and found a few similar suggestions.
Many privacy suites have this feature integrated, and I believe CCleaner should also.
The reason is simple: some people, myself included, prefer CCleaner erasing cache, cookies, etc. with secure file deletion methods, such as DoD 5220.22-M or NSA.
I am fully aware of the built-in scheduler for Windows, but that is not sufficient. You cannot make CCleaner run on browser shutdown, and having the function implemented in CCleaner would be much better.
When CCleaner runs on 'auto', it should open a window instead of running silently in the background.
Please consider this suggestion.