If it meant they improved their prospects for economics, culture, etc. then sure, but it wouldn't. And currently it wouldn't for Texas. But if at some point people thought it would be a better deal to be independent for economic or ideological reasons, why should violence determine whether they stay? Might as well just put it to a vote. Britain has got that right, they have let their former colonies leave (mostly) peacefully. And in the case of Scotland, they have even stronger historical ties and integration than a lot of US states, but it was actually put to a vote.