From what I have gathered off of the warez and hacker sites I know of, the hackers are claiming they did it because it was their duty to do it.
Evidently Half-Life 2 was due out Last month but was put off. The hackers felt it was their God given duty to steal the game and release it on the net.
IMHO they are nothing more than clever thieves who should be hunted down and hung from the highest tree with a sign around their necks that reads:
"I stoled HL-2"
(Side note: I hate Word Perfect. Give me Word 2000 any time.)