1. Many Protestants who are switching to Catholicism or considering being other than Protestant are persuaded more through historical research and less through doctrinal compulsion. Historically, the Augustinian monk, Martin Luther, seems to have had a very specific problem with the Roman Catholic Church, and that was over the sale of indulgences. In fact, the 95 Theses he hammered on the Church door of Wittenberg was 95 reasons why he disagreed with the sale of indulgences, not 95 different problems he had with the Roman Catholic Church.
Because he kept pushing for a fair hearing, he was excommunicated from the Roman Catholic Church. To protest, he publicly burned the papal bull carrying word of his excommunication. The word Protestant invokes the idea that each person is bound by his conscience before God and that no man can be an intermediary for him in the area of personal responsibility (aka, conscience). The Church's unwillingness to give a fair hearing galvanized Luther's decision to throw off that oppressive aspect of Rome.
2. Many Protestants realize that the effects of Protestantism should go well beyond their church doors, but they do not. Luther's problem with Rome was the prerogative of God in salvation, so he stood for the "sovereignty of God" in the area of personal salvation. John Calvin came on the scene and completely reframed Luther's problem from "soteriological sovereignty" (God is sovereign over salvation) to "cosmic sovereignty" (God is Lord over everything). Calvin did not just give us doctrines, an intricate systematic theology, as the story goes. It also wasn't Calvin who codified the truncated TULIP idea. He never would have been so facetious.
Known for more than his "doctrine", Calvin is the Father of Constitutional government. His thought-form ended the prominence of monarchical rule because he extended the idea of personal responsibility from Luther's "conscience" (which was Platonic, and, therefore, incomplete) to "matter." So every country that has a constitution, every church that has a constitution, and every business that has a "constitution" clearly delineating rights and limitations of the individual can thank John Calvin. Without Calvinism, you would have no America, no democracy, no Walmart.
So not only are North American and much of Europe politically "Calvinist", but every nation struggling to create a constitution providing liberty for all its inhabitants in Eastern Europe or the former Soviet Union or Russia or Africa or parts of South America is under the "umbrella" of Calvinism whether or not they succeed. I am not describing the Calvinistic witch-hunters of New England, nor am I talking about the stereotypically ascetic lives of the Puritans which in this sense should be treated separately. I am speaking about the mother-thought of Calvinism that maintained a "high" view of God over the soul and the body, over the idea and the actual, so that it actually "touched" thought and matter. Affecting thoughts. Affecting matter.
3. Many Protestants do not see an end to the never-ending splintering of Protestantism. I find it interesting that many of the Charismatics, Pentecostals, Baptists, Primitive, Bible Churches, Church of Christ, Methodists (the list goes on and on) do not recognize themselves to be within the Protestant train. Many of these denominations list themselves as "Independents" which ironically makes them more Protestant than they care to imagine. I hear versions of the following statements all of the time:
Our church is different than other churches because we take the Beatitudes of Jesus seriously. Not living by the Beatitudes is why our culture is godless.
The answer to our country's crisis is that we aren't having enough children and leading them to Christ. Our church's distinctive is that we are 100% against birth control and we have several children's programs
We believe that God is angry with America. The only way for our country to escape the coming judgment due to homosexuals, mixed swimming, dancing, and socialism is to repent
It doesn't matter the perspective: the distinctives go on and on, ad nauseum. Pastors and church leaders spend hours and hours in meetings absurdly designing "this" angle or "that" angle to bolster numbers, to bring in money, to garner more influence, to consolidate power, to protect assets, and all to what end? What will happen when the dog catches the car?
These kinds of independent streaks within Protestantism are not to be celebrated. Diversity is inherent within the created order without having to artificially create new categories. Further, these independent churches largely do not see themselves in relationship to each other. You have heard the "Body of Christ" analogy: each church sees itself as the Body of Christ so that there are literally millions of mini-Christs out there. Which one is the authentic one? In short, many independent churches do not see how they can survive unless they remake themselves, update themselves, or change altogether.
My personal Protestant roots go deep, though I recognize Protestantism to be a drop in the bucket and my own contributions to it to be minimal. Actually, I have no noteworthy aspirations within Protestantism (none that any would consider noteworthy anyway). I do not know where the next decade will find the never-ending diversity of Protestantism to be, but at the rate it is running through its creative options I do anticipate an Islamo-Protestant amalgamation of some sort. You can bet your bottom dollar.