I don't think most suicides intend to be cruel. They're so caught up in their own pain that they can't see outside themselves, and depression has often twisted their perceptions to where they truly believe no one will care, or even that the people they're leaving will be better off without them.
I suspect the same thinking often goes into leaving. Back when I was suffering from post-partum depression, I nearly walked -- and I would have thought I was doing spouse a favor by leaving, so he didn't have to cope with me any more and I couldn't inflict any more psychological damage on him or the kids. It wasn't true, of course, but I wasn't capable of seeing that.
And sometimes people leave because they think they have to save their own lives. People trying to deal with sexual orientation issues often feel this way -- that staying where they are is killing them inside. They don't want to hurt the people they love, but they can't keep hurting themselves, either.
I'm sure there are people who kill themselves for malice. I'm sure there are people who leave in order to inflict pain. I suppose Steven might have intended to hurt his parents and his family for not understanding him or whatever -- but I think it's more likely he was sufficiently depressed to think that that they were better off without him. Now he probably thinks he doesn't deserve to be found.