Whilst I enjoyed that episode, it was fictional. Did Picard really need to be stabbed in the heart, just to learn his lesson? (And, his 'unremarkable career' seemed to be a bigger criticism of Starfleet/the Federation than we normally see - what's wrong with an ordinary life?)
I would be happy to remove the trauma that I experienced in my past. I'd take the risk of being a different person - with different good qualities.
This is Q we're talking about. He's not the kind of character who would sit down with Picard over a cup of tea and talk him through why changing his past would change who he is. Humbling Picard by showing him the folly of his wish to change the past, while he lay on his deathbed, by making him choose to get stabbed through the heart is definitely more his style.
Also, I don't believe they portrayed Picard's "unremarkable" career negatively, except in Picard's own view (and Q's I guess).
I would be happy to remove the trauma that I experienced in my past. I'd take the risk of being a different person - with different good qualities.