Bad Experiences
Experiencing bad experiences is important for two major reasons. On the one hand, you'll be able to confirm if something is truly as bad as you imagined.
On the other hand, only by having a bad experience as a contrast can good experiences really stand out. If you were to remove bad experiences, all you'd be left with were the good and normal ones.
Of course the "normal" methods would need to be adjusted due to them no longer being considered as average.