Sure they are not useful against burglars, or even muggers. But what about rioters? But of course the Second Amendment is not (solely) about *personal* self defense. It's about defense against tyranny. HE bombs, deep penetrating variety especially, could be quite useful against tyrants. TOW missiles work well too., as Saddam's sons found out.
Besides, what if I just want to set them off on my in law's 200 acre farm? That wouldn't hurt anyone, innocent or not.
We have to stop trying to prevent people from doing bad things by banning inanimate objects, and start working on bad people. Criminals and terrorists don't obey gun or other arms control laws, they only affect the law abiding.
You, as an individual, are not empowered by the Constitution to declare war on tyrants; that is a power reserved to Congress by We the People. They also hold the power to authorize individual acts of war, via letters of marque. Should the tyrants be members of the existing government, well then gun laws and the Constitution are moot at that point anyway.