While it's OK to loose some of the memories because they are not needed and the mind has a natural mechanism to remove excessive memory to make space for new experiences. But if you don't remember your past, important people, events and dates it can be tormenting as if a big piece of your past and your identity is missing. Again, the minds defense mechanism protects you from what is emotionally painful. Repressed memories is one such protective way to protect you from feeling the pain often. But if you resort to this defense frequently, then it may be an ineffective way to deal with pain.