I wouldn't have minded if Harry remained an ensign, kinda like Segal's character in Under Siege was a cook.
At a certain point, Harry was the most by-the-book person on the bridge crew, but I wouldn't have minded if Harry's story was that after Voyager returned he kept getting into situations where he had to break Star Fleet rules, and because he wasn't a prestigious captain just kept getting busted down to Ensign. But anytime some hairy situation demanded experience and skill, Harry is always the first person his commander calls.