|The link I provided showed that several prior presidents have, as you say, "inserted themselves". |
One aspect of your analysis of the event that I can agree with is the GOP vs. Dem party members receiving special "tickets" (for lack of a better term). On that point, I agree with you that Trump was wrong for doing that, his thin skin wouldn't allow for him to be the bigger person, or at a minimum, the President of all Americans, regardless of party affiliation.
I realize what type of "military parade" you are referring to, however, I do not believe this was such an event. You asked why senior people in the Pentagon were opposed to it, my guess would be that because it is Trump, they were not sure that it would not become a political event. I think that would be a fair concern considering Trump's record. Trump has earned people's skepticism, that much is on him; at least the skepticism from those who are not automatically against it JUST because it is Trump. In the end, when viewed objectively, it did not turn out to be the political spectacle that many on the left feared.