Do criminal(black-hat) hackers serve a useful purpose?It seems to me that a lot of "black hats" try to justify their actions by saying something along these lines.If there wasn't a criminal element in the computer world would security be near as advanced as it is today?

Then "white-hats" tend to counter this by saying that there wouldn't be a need for security if there wasn't a criminal element to deal with.

It seems to me that these are both good points,because although there wouldn't be a need for security if the criminal element was taken out of the equasion,it would be disasterous if somebody did try to bring down the worlds major computer networks.
Hmmmmmmmmm.What do you all think?