Just an idle suggestion. I know the allowance of plugins can make a program more complex to write - but it would add a lot of customization to CCleaner. I've been thinking on ideas for plugins too - like the redirection of the deletion of files via ccleaner to something like Eraser. Regardless, I think this warranted a query. Hope to hear if anyone agrees or disagrees!
I have never come across plugins that are combined with tweaking programs and perhaps its a bit unlikely. Perhaps a new tool on CCleaner rather than a plugin would do.