All of these figures, incidentally, strike me as implausibly high, and if they were palpably true it would be troubling. Secession is illegal, however, and even if it weren't, every state is clearly better off as part of the United States than it would be on its own. I therefore understand secessionist rhetoric--in Texas and elsewhere--as a euphemism for more general frustration, rather than a serious suggestion. In fact, I would argue that it's precisely because secession is such a preposterous suggestion that it's safe to clown on about; that's why some people in Austin have started up their own petition to secede from Texas if Texas secedes from America.
I'm kind of interested in the question of whether a state should have the right to secede. If states are supposed to be sovereign entities than I would think they should have the right. But since we don't have to deal in strict terms all the time, we can easily say that their sovereignty has limits. And we figured out after fighting a civil war that the ability to secede is beyond those limits.
Setting those limits was a big reason the founders got together and wrote the Constitution. States had too much power. So we gave the federal gov't power over the states in order to create a strong nation. Granted, we've gone down a more Hamiltonian path in regard to federal power than people like Jefferson or Madison would have wanted. But the supremacy clause and the inability to secede exist for good reason. It's not perfect; see our federal drug laws. But I think it's better than the other option.