I don't think that bad memories are forgotten since that's impossible and like you already mentioned it's a WARNING and we should learn from it. If you burn your hand if you grab into the fire and forget it you will do it over and over again.
If you are raped, beaten up, are a war victim, no way you forget. It's just what we tell ourselves or others. There's a very good reason why many suffer from trauma and depressions and the solution isn't given by therapists, doctors with pills or burning a peace of paper with what happened to us.

What is important is to admit it happened and give it a place in our life with the conscious that it will never be forgotten. If that would be the case the madhouse wouldn't be crowded, the hospitals not full and people would be way more happy than what we see around us. Also those with Alzheimer's Disease proof that memories remain and I would find it terrible if I had to relive my childhood again because I try hard to forget it and pretend it never happened.

Good memories? I find it hard to see or have them so I create them just like many others like me do. It's the only way to make life bearable and worth living.

Thanks for adding the happy monkeys!.