losing Harry was definitely an improvement.
I'm not sure I can agree with this. Yes, his role as a surrogate Ian Chesterton or Jamie McCrimmon was basically made redundant when Tom Baker was cast as the Doctor, but Harry does show a definite chemistry with both Baker and Lis Sladen, and the more ensemble feel (Doctor, Sarah, Harry) of Season 12 gives it something that I felt some of the following seasons sometimes lacked. I'd have liked to have seen Harry retained to see how far they could develop that dynamic.
Agreed. I liked Harry, and even though Baker could be more of the "man of action" than someone older (though, what the hell, Pertwee's Doctor really was a man of action, action, action), Harry's masculinity was a nice foil for Baker's childishness and brains.
It was an interesting dynamic.