Well, Big Jim, it would probably be a good idea to clarify things for our Service Academy friends.
We, and I assume you, referred to anyone who begins with a freshman class in the Fall semester, as a "fish". Anyone who joins later, including the second semester fish year, is a "frog". In my day, frogs could join as late as the fall semester of Junior year.
Frogs generally did not have an easy time, and had to work pretty hard to gain respect. There was resentment that they did not go through all the crap that everyone else did, who showed up on Day 1 of the fall semester.
And the bonds of friendship that formed during the training (never call it hazing) of the fish year were forged quite strongly by enduring training together. Those that joined later missed some of those bonds.
That being said, some of our frogs became a beloved part of our class, and we respect them and accept them today, with zero thought of when they joined.
There were various ways that frogs were integrated. Some did as you say, a semester as a fish, then jump to the academic class with which they belong. We had one guy, as I said above, who did an entire fish year, then joined the junior class at Final Review, skipping the sophomore year. I think today's Corps does at least one semester as a fish before jumping them to their academic year.
When you say that "back in the day" the Corps decided, not the Commandant, well, that's not today's world. Even in my day, we had a lot of autonomy on the Quad, and you seldom saw a Bull outside of ROTC classes. If you did, it was generally Not Good News.
Today's University controls the cadets a lot closer than we ever were, and I suspect we were controlled more than you. The Professor of Military Science is no longer the Commandant, General Ramirez is under the Department of Student Services (I think). As much as I appreciate Joe, I don't think that's a good arrangement, but that's a different discussion. I will say that in my son's day (class of '09) it often seemed that the NROTC detachment was at odds with the Corps in several facets, and that was not good.
We are in a Zero Tolerance world, and a cadet's misdeeds would be around the world on Social Media before the miscreant got back to his dorm.
So the University allows much less autonomy than back in our days, and the cadets have fewer opportunities to make small mistakes and learn from them. Which means that they often avoid small mistakes on the way to HUGE mistakes that blow up on them and our school, with dire consequences.
It's less of a leadership lab, if you're not allowed to lead.