It does not just mean "cool". What you think is cool I might think is stupid or offensive. Either way, we do what we want, we are based. The fact that Honey Boo Boo is reviled just shows that she epitomizes based.
Based is in the eye of the beholder, yes, exactly like what's 'cool' or not. Two different groups can disagree about which words apply to particular things or people while still holding the same usage/meaning for the words themselves. Like 'cool' and 'lame'.