Morally, it's also not just how you break in, but what you do afterwards. I.e. if you prevent more harm than you do.
If you enter the unlocked door and write "HI YOU FORGOT TO LOCK YOUR DOOR" with lipstick on the bathroom window, you're alerting the owner to a bad security practice by giving them a good scare. It is A Good Thing, because you likely prevented them losing their stuff.
If you enter the unlocked door and start smashing and stealing stuff, you are technically still alerting the owner to a bad security pracice, but it is now A Bad Thing. By "being" the worst case, you only guaranteed something that was only likely to happen.
Morally? Isn't privacy important to you? Leaving the moral judgement up to what the intruder does with the data he finds seems a bit delayed to me. He is immoral from the get-go, by trespassing in the personal property of others. It does not matter if I forget to lock my door. People often do. It does not make it OK to open my door.
You probably have this opinion because you think it's the cool way to think, that these 'hackers' have a great function in society, but lets shift the analogy: do you think your government should be able to do the same? If there was a story about the US government doing this stuff, HN would go insane with tirades about how the government is out to get us.
But no, not if it's lulzsec, not if it's some cracker kid. It's the romantic fantasy of the teenage computer hacker, rebelling against the world and saving the day... I mean posting your nudes on facebook. Everyone here emphasizes with it so much that they're blind to the reality that it's just wrong to invade the privacy of others, under any circumstance.
The only exception I could think of would be to invade the privacy of an oppressive government.
