Protestants accept Christ as the only true head of his church. If the primacy of the Pope as head of the Roman church nullifies 'denominationalism' within the Roman communion, then certainly the same principle of unity will be granted for Protestantism? That is precisely the contention of many Protestants regarding the spiritual unity of the church in Christ, regardless of the polity or structure of worship within any particular denominational expression.
You wrote: "The essence of Protestantism is that one is free to reject what one personally feels is not compatible with scripture - and that one's personal feelings on any given matter trump any Church doctrine."
Surely you must know you are engaging in a bit of hyperbole here that is not at all honest or accurate. One's personal feelings trumping 'Church doctrine' is not the essence of Protestantism. That the Bible is the supreme and only rule of faith and practice is the Protestant principle. However, the Bible is interpreted within the larger community of the church from the patristic era down to today. The creeds, councils, the fathers and the confessions of the catholic church (including the Biblical insights of the Roman tradition) guide and inform the Protestant.
Mystics may allow 'feelings' to trump ecclesial doctrine or the witness of Scripture, but mysticism is not Protestantism.
You wrote: "The only unity among Protestants denominations is that they reject Catholicism as the way to follow Christ. Beyond that, the doctrinal differences among the thousands of Protestant congregations are endless to the point of absurdity."
Again, you are obviously moving beyond the truth for the sake of rhetorical impact. To assert that the 'unity' found in Protestantism consists only in a common rejection of Rome is itself absurd on its face. Protestants are united in their affirmation of the creeds - if not in fact, then at least in substance. Both the Anglican and the Primitive Baptist affirm belief in the Triune God - Father, Son and Holy Spirit, for instance. It is also false to baldly assert that Protestants reject Rome. Protestants maintain the witness against the abuses and corruptions in faith and practice which crept into the church by the beginning of the second millennium. With deference to my fundamentalist sistren and brethren, I would note that the PCUSA and many other denominations are engaged with Rome in ecumenical dialog. The Roman Church acknowledges Presbyterian baptism as valid, just as Presbyterians have always acknowledged Roman Catholic baptisms as valid. Protestants are united in the common faith of the catholic church down through the ages. They are united in many ways with our separated brethren (wink, wink) in the Roman Church - though on issues of ecclesial/papal authority, the definition of justification, the relationship of justification & sanctification, and a few other fundamental and substantive issues there are barriers yet to be overcome. However, at least in the Reformed tradition, even Calvin was willing to accept Papal authority, as adiaphora, if the substance of such issues as justification, worship and the sacraments were reformed according to Scripture and the patristic witness.
You are denigrating Protestants for the most invalid of reasons - reasons that in reality do not exist. As a postscript, I would note, as you are no doubt aware, that it is not only Protestants, but the entire Eastern Orthodox communion, that rejects the primacy of the bishop of Rome.