As you might expect, the worry is that a hacker with access to your photos could use a script to recover any information you want to keep private, such contacts or trade secrets. The information could be used by the offender for espionage, blackmail, or harassment. For locally stored screenshots, this may not be a major problem (you have more issues if an attacker already has access to your device), but for unaltered photographs you keep in the cloud, it could be highly problematic.
