Hope-- I'm not saying desires are bad, just that a perfect being should not desire anything. Your lack of a horse does not make you "bad" but it does mean you are not a perfect being.
I think the most important question here is the title of this thread: Could God have acheived any good He wanted without allowing a massacre? If God is all-powerful, the answer should be "yes". However, if God could have acheived the same good that supposedly came from the massacre without allowing a massacre, and yet He still chose to allow the massacre, that implies God is not All-Good. The only option is to redefine that which is "good" to "anything God wants or chooses to allow" (which, come to think of it, would solve a lot of problems with the genocides of the Old Testament). Still, by that definition, Satan and demons and murder and rape would all be "good" and "evil" would not even exist.
Whenever I discuss the Problem of Evil with others, the image I get of the Judeo-Christian-Islamic God is one who much more perfect than we are, much more powerful than we are, and (on some levels) much more good than we are--but not infinitely so. If God was infinitely perfect, infinitely good, and infinitely powerful, everything should hypothetically be perfect and good, all the time, period.