why was it a bad move?

Not sure if this is the right place to post this. When you run the chess analyser, it says “mistake - a better move would have been...” and then it shows you the better line of play you could have followed. However, so that I can understand why it was a mistake or blunder, I need to understand what the outcome would have been - so it should show you the line of play that leads to why it was a mistake eg if it leads to losing a piece or similar.

Does anyone else feel this way? I feel I would learn more by being shown why it was a mistake and what the consequences would have been, rather than being shown what a grandmaster would have played in the same situation

Sounds like you would like a chess coach / mentor rather than a chess engine.  I suggest finding someone stronger than you to go over your games with.  Doesn't need to be a GM.