I do not for a second deny the issues, difficulties, or concerns. They are entirely valid.
The problem is that you can't simply set aside problems that lie at the heart of the very enterprise, waving them away to be sorted out after the Reformation comes. It's easy to be in favor of establishmentarianism, if that remains a very vague concept that everyone is free to define in their own way. It's harder if you have to wrestle with exactly what kind of establishmentarianism you think Scripture requires. At one end of the spectrum you have what we might call "hard establishmentarianism", in which only worship within very narrow boundaries is permitted in your realm and those who disagree are still forced to go to your church, where they may or may not be able to be members and/or take communion (see part 4 of the article you linked to). They cannot have their own churches however. You may graciously agree not to imprison them, but they don't get to vote or hold public office. It's not clear if they are permitted to teach their children their beliefs. At the other end of the spectrum, you have the current set up in the UK where a very broad church is "established", and has a few advantages (bishops in the House of Lords), but in practice other denominations are free to do whatever they want, within reason ("soft establishmentarianism"). You could hold a position at a variety of points along this spectrum, but it is reasonable to ask you to define exactly which establishmentarianism you want us to vote for.
I suspect most establishmentarians here lean toward the former, not the latter, but don't seem to have though through the implications. Everyone seems to assume that the established denomination will exactly match their own doctrinal preferences, and they will have arrived at a utopia in which every church in the land is just like theirs. No one seems to imagine it possible that their own views might end up getting suppressed and persecuted. For example, the current Free Church of Scotland holds to the establishmentarian principle, but it believes that it should be the established church, not the Church of Scotland. Yet if hard establishmentarianism held sway, they wouldn't have the freedom to argue that they should be the true established church. They would be forced to go to their local Church of Scotland church and sing hymns and hear vague platitudes along with everyone else.
And if OT Israel is our model, that doesn't give us a whole lot of comfort. They were never, as a nation, on board with the true religion. Every now and then a godly king dragged them forcibly back in the right direction, with the help of a brief and very limited revival. But more often than not, his son re-started the idolatry. It's similar in church history; for every godly leader who helped and encouraged reformation (and there were some signal examples), there were five who persecuted and suppressed the true religion. As I result, I for one am less than excited about the idea that the State enforces a single denomination and suppresses the rest. I'm open perhaps to a kinder, gentler establishment - one in which I don't have to sort out all of my neighbors theological problems, just the ones in my own church - but not the full strength variety. We'll all get our doctrine straightened out perfectly in heaven (including me); until then, I'm okay with the idea that some of my brothers and sisters in Christ aren't getting everything right, and I prefer to defend their right to be wrong than abandon my own right to be right (as I understand the Scriptures).
Oh, and in the meantime, that doesn't prevent me from praying regularly for our present leaders, pagan and Christian alike, in hopes that they will give us a quiet life in which we may pursue godliness according to our understanding of the Scriptures.
, will be much closer to the throne than I, conscientiously believe that it is wrong to take an oath to the Constitution. As a result, they cannot, in good conscience, hold certain jobs that require them to take the oath. Should the Constitution (or perhaps the very idea of constitutional government) be scrapped because of their conscientious objection? Or do the rest of us just see that outcome as the unfortunate result of a misinformed conscience?