Many users use their trashcan as a "safe" delete location to be evaluated from time to time. CCleaner empties the trashcan per default. I suggest that the default does not include the trashcan to avoid unintended deletions. (Yes, not all people run regular or even automated backups)
It is very much recommended not to do this, as mentioned here:
https://www.jnttek.com/proper-file-management-a-k-a-please-dont-save-your-files-in-the-recycle-bin/
https://www.digitalcitizen.life/simple-questions-what-recycle-bin/
as even without emptying the Recycle Bin manually, running a program like CCleaner, etc, Windows will automatically delete older files if the Recycle Bin would exceed the space allotted for it, so it's most certainly not a safe storage space.
Additionally, with the Recycle Bin being the most visible place for 'trash', it would also seem very odd if the software didn't clean this.
Nonetheless, I'll certainly bring your suggestion to the attention of our development team for further consideration! Please feel free to leave any other suggestions you might like as well, either here or on the Ideas Board linked from the forum's main page.