Sure if you encrypt with an application-level key it makes it harder for any adversary to use your data, as he/she will need to not only get access to your data

Sure if you encrypt with an application-level key it makes it harder for any adversary to use your data, as he/she will need to not only get access to your data but also obtain the encryption key to do anything with it. Encrypting data like this is easy and can drastically reduce your attack surface.