I’m personally of the opinion that revenge is morally dubious as all hell; but it undeniably makes a great story engine for a piece of fiction.  It gives your character a large and important (and possibly dangerous) goal to work toward; it implies an interesting backstory of some variety; it insures that your character is either going to have to get off his duff and do something or at the very least spend some interesting screen time justifying the fact that he isn’t; and it provides lots of hooks on which to hang moral and ethical and social debate if you go in for that sort of thing.

As plot devices go, you can’t beat it with a stick.