When it comes to hacks against corporate or government targets, it is entirely plausible that in many cases the public disclosure itself is of more importance to the hacker than data breached. Stealing 100,000 credit card numbers may only net a few thousand dollars for the hacker, but the damage to the company targeted could cost tens of millions of dollars.
Also, hacking could be leveraged purely as a tool for manipulation of public opinion, not necessarily opinion of the target itself but rather about information security in general. For example, imagine if someone stole the web browsing or phone call history for all the candidates currently running for US president and then posted the data on the web. A logical first reaction would be to suspect that it's a partisan attack by the opposition in an attempt to influence the election, but then again maybe not. The motive might only be to spark a debate about digital privacy legislation and impact the candidates in a personal way that motivates them into action.
"Do not seek to follow in the footsteps of the wise. Instead, seek what they sought." - Matsuo Basho