Natural it may be - that doesn’t guarantee it’s healthy or legitimate. The CC was pretty Catholic in 1517, but that did not in the least mean it did not stand in dire need of reform. Catholicism is all very well, but it does tend to appeal to the “natural man” in a way that evangelical Protestantism does not. Whatever may be said against the Reformers, the Catholic reformers did not turn back the clock to the days before the Reformation - they could hardly do so without implicitly excusing the abuses with which the Council of Trent tried to deal.
Besides, “alienated themselves” when ? I think this is important, because neither the CC nor the Protestant Churches have stood still - those who were never RC can hardly be said to have alienated themselves from the CC in the same way as the earlier Reformers. And it takes two to have a division. Rome is bigger than Protestantism; that does not mean it has not been as truly divisive. And the reasons for Christians not to be in communion with one another don’t depend solely on the existence of past scandals such as the indulgence-traffic, or even on more recent events like the brutalities against Protestants in Bohemia after 1620, or even entirely on definitions such as those of the Immaculate Conception & Papal Infallibility - events in 1517 & soon thereafter play a part in deterring overtures to Rome, but they are not by any means the only deterrents. So the reasons for coolness toward Rome shift a bit with time, but are not non-existent.
Besides, what is Rome’s real attitude to Protestants ? That may seem an absurd question, even insulting - but if Protestants don’t see a close fit between the milder statements they hear from Rome, & the lives of the RCs they know, they are unlikely to be favourably impressed. The CC has a lot of history to live down, & if RCs say things or seem to say things which fit with the picture of a persecuting & intolerant Papal dictatorship, this puts people off - quoting Dignitatis Humanae is not enough to assure everyone of Rome’s bona fides.
ISTM there’s fear & suspicion on both sides - humanly speaking, this is insoluble.
There are genuine issues of theology & doctrine, & they do get in the way of reunion. ##
Furthermore, the term is coming to be used as a broad catchphrase to cover a lot of very different things. No one really knows what it means, but everyone is excited about it (one way or the other). Like so many Protestant movements, it’s anything but a “denomination”–it’s a very loose set of trends.
For instance, a friend of mine who is a Methodist pastor has been labeled by his superiors as a proponent of the “emergent church.” They say this because he’s taken a struggling, working-class, rural Indiana congregation and taught them to appreciate the lectionary, the sacraments, etc., while maintaining a very informal, folksy tone (when I visited his church, he sang a Charles Wesley Eucharistic hymn while the people received communion–he was dressed in an alb and accompanied himself on the guitar to a folk-style tune of his own composition).
This does not sound so very unlike the ways of the Anglican “ritualist” clergy, who combined zeal for the betterment of the the lot of the poor with a zeal for liturgical splendour. At the time, they were heartily vilified by their more Protestant brethren as crypto-Papists & “Romanisers”.
It may be worth pointing that the Oxford Movement had plenty of repercussions in the USA - though one can’t expect Catholics in the USA to have heard of this, unless they’ve heard of converts to Catholicism like Bishop Ives.
St. Aidan also comes to mind - though he lived even longer ago. ##
Is this really “emergent church”? I don’t know, but I think it’s great (though no doubt it reminds some of you too much of 1970s Catholicism). I know my friend’s theology enough to know that he really is concerned to be faithful to historic Christianity, and that he’s very favorable to both Catholicism and Orthodoxy. So if this is emergent church, then emergent church really is a form of crypto-Catholicism. But I suspect that you’re right, and the more standard “emergent church” types are far less Catholic in their theology.
Should that be “Catholicism”, or “catholicism” ? Your description, so far as it goes, doesn’t seem to be of anything unmistakably Roman.