I start every single visit to Gettysburg by stopping first at Bufords statue. Without his vision, leadership and guts the battle, and possibly the war, would have turned out much differently.
I have always wondered how differently some things would have turned out if Mr. F.J. Hooker had named Buford to head the Cavalry instead of Pleasanton. Joe later admitted that he should have done so, but instead he made Buford to lead a reserve brigade despite him having been Chief of Cavalry under both McClellan and Burnside.
Hooker made some boneheaded decisions but that one has to rank right near the top. That army needed more men who, like Buford, actively wanted to fight rebels.
As you may know, I have devoted much of my adult life to the study of John Buford's life and career. He plays a major role in a number of my books, not the least of which is a monograph dedicated to his role in the Battle of Gettysburg, and I have also published a number of articles that also deal with his life and career in various ways. These are questions that I have often wrestled with.
Your point is well-taken, of course, but the reality is that in an army where seniority meant everything, it wasn't going to happen. Pleasonton outranked Buford by virtue of his commission as brigadier general of volunteers pre-dating Buford's by a couple of weeks. Given those hierarchical issues, there was no way that, at that point in the war, FJ Hooker could have promoted Buford over Pleasonton. It just wasn't going to happen.
You say that Hooker "made Buford lead a reserve brigade." That simply isn't true. While Buford was entitled to divisional command by virtue of seniority, he very explicitly REQUESTED that he be placed in command of the Regulars when the Cavalry Corps was formed at Hooker's order in February 1863. That was not a slight--it was granting Buford's explicit request.
I content myself with the words of John Gibbon who, near the end of his life, wrote that "John Buford was the best cavalryman I ever saw." That's good enough for me.
For me, the better question has always been, had Buford not died of typhoid fever in December 1863, what would he have accomplished as commander of the Army of the Cumberland's Cavalry Corps, which position he had agreed to accept just before falling ill with the typhoid that ultimately took his life.