I think those two issues you touched on run a little deeper than your analysis.
First, it may be true that Hughes didn't take a huge step he still put up way over 2 points per game. That's dominant plain and simple and I don't think he should be docked for being a dominant player as a 16 year old. He put up 112 points in 50 games. So would you like for him to take a step forward, sure, but how much better can you expect from that type of performance over a whole season? I think short of doing something similar to Kane or Matthews, there just wasn't a ton of room for growth where he was playing. Pronman said that Hughes (and the whole US team really) were not challenged enough and to me it seems pretty clear that Hughes was toying with his food. If he should be criticized for anything I think it's the fact that he stayed with the program when he could have gone to the CHL where it would be easier to measure him, but in terms of on-ice play, I don't think you can criticize him too much. I also don't think his situation is comparable to Patrick's at all. Patrick put up pretty good numbers over less than half a season, Hughes put up dominant numbers over a whole season.
Second, Hughes may not have had the best moment in the tournament like Kakko, but in reality he only put up one point less than him and had a higher ppg. If you ask me Kakko did upstage him, but I don't think his performance was lackluster. Plus you also have to factor in that both US teams (Junior and World Championships) were a little deeper than Finaland and Kakko played a bigger role.