apple has been sued a lot by the stupidest things. for example the beatles sued them for having an apple as a logo when the beatle's logo is a straight up image of an apple and not even a real designed logo. everyone wants a piece of them pretty much and they do get ripped off plenty, but they get ripped of in very general ways that they really can't defend in court so my guess is that they are trying every patent they can to make their case.
you can't deny the similarity in many phones that have popped up that look and work just like an iphone. many have the same icons used in OS X just slightly different colors. they are profiting over Apple's image and desirability and they can't do much about it, so they work different angles.
at least apple fights other companies and not it's own clients as much. there are no license keys for their OS for example. yes there is DRM in iphone and there was DRM in music, but they are selling OTHER PEOPLE's stuff on it and they are pressured to protect it. the drm back in the ipod was not their doing it was the music companies and they take the blame for it.
look at nintedo. they go far and wide to protect their own games and not third party games. nintendo is truly greedy.