"Hacking" is the ability to disassemble the structure of how something logical works.
There is no problem with ethics there.
I would imagine what you are referring to is "Cracking".
If there is no malicious intent or creation,
and it does not negatively effect any other person's or organization's property you are pretty well safe in my mind.
IE. The basis lending towards genuine self education in a positive light.
As soon as you get knowledge and try to use it to effect something outside of your domain,
then there should be cause for concern I'd like to fashion.
Intent is key.