And what if the full backup that completed successfully won't restore? Completing doesn't mean it's good. If you're using RESTORE VERIFYONLY, that checks the header of the backup file only.

So, you delete all the tran logs before the full backup. Next day something goes wrong, you go to restore but the full backup's damaged and won't restore. The tran logs are gone, so assuming you still have the previous night's full backup, you restore and lose ~36 hours of data. Is that acceptable?