This won't matter 10 years from now.
Whether or not I'll care about something in 10 years has absolutely nothing to do with how important it is to me now. Even when something no longer elicits an emotional reaction in me, I still care about what happened at the time. I NEVER look back and invalidate my own feelings of the time, no matter how young I was.
You won't remember any of this 10 years from now.
I remember perfectly well what went on 10 years ago and how I felt about it. See previous answer.
You'll look back at this and laugh.
I may laugh about a situation that was embarrassing or just ridiculous, but I'm laughing at the situation itself, not how I felt about it or reacted to it at the time. Usually I can tell in the moment whether or not I'll look back on something and laugh later on.
You'll look back and realize that there was nothing to worry about.
Say I was afraid to enter a person's yard because they have a mean dog that might chase me, but then I enter the yard and the dog isn't there. Yes, I know now that there was no real danger, but that does not mean that I had nothing to worry about back when I didn't know whether the dog was in the yard or not.
You'll understand why [authority figure] did what they did when you're older.
If someone pushed me into the pool when I didn't know how to swim because they knew that it would teach me how to swim, that would not be okay. Even if there was a lifeguard standing in the pool so it wasn't dangerous, just the fact that the person caused a really miserable experience for me makes it not okay. The fact that something "worked" on me will never make it acceptable to me.
If something sucked for me when I was younger, I'm happy if kids don't have to go through the same thing anymore. I never think that someone should have to go through something just because I did when I was their age, especially if that something was not okay with me at the time.
If you run into your former classmates when you're grown up, you'll just bond over the fact that you went to school together and all the negative stuff won't matter anymore.
This one is possible, but for a different reason. When I fought with other kids when I was younger, I did a lot of hurtful things that I wouldn't do now. So if a classmate hurt me when we were younger (nothing severe or traumatic), I assume that they might not do the same thing now that we're older. I am more likely to give my peers a second chance than adults. Also, sometimes you don't get along with someone because of the situation you're in. At my middle school, we had a dividing line between popular and unpopular kids. I knew that some of the popular kids were nice, but because our cliques weren't nice to each other as a whole, we never really talked to each other. When I met up with one of my popular classmates outside of middle school, we got along really well. The passage of time doesn't mean that everything is okay in spite of what happened - it means that things might be okay now because they might have changed.
Don't you ever read something you wrote in your journals years ago and feel like you've moved on? Like it doesn't elicit the emotional reaction in you that it once did?
If I read in my younger journal: "I can't wait for my friend to come over tomorrow! We're gonna play hide and seek and make pillow forts and have so much fun!" I would not feel as excited about it right now because, well, my friend isn't coming over tomorrow to play hide and seek and make pillow forts. But I would feel happy remembering how much fun we had at the time of the journal entry. I would not look back and think it was silly that I felt excited just because the same thing doesn't excite me now. The same is true if I were upset about something; I may not feel upset reading about it now, but I would never think it was silly that I was upset at the time.
Don't you ever look back and think you wouldn't feel as bad now about things that once upset you?
If someone were pressuring me to cut my hair every time I saw them, it would bother me less now than it did in middle school. But that's because we're not in middle school. Now, I would have much more control over how often I interact with this person, even if we were working together. As we get older, our situations change. It's like moving a plant from a dimly lit room to a sunny room, watching it grow and blossom, then deciding that because it's strong and healthy now, it will be fine going back into the darker room. That might be true, but it may just be blossoming because now it's in the sunlight.
If you could go back, don't you think you would react differently?
When I look back and wish that I had done things differently, it usually involves standing up more for myself and my friends, and taking more drastic measures to solve problems and get out of bad situations. So yes, I would react differently to the same problems, but I would do more about them, not less.
You can't write well about things you're too close to. You need to wait a few years.
This is somewhat true, but when I read things I wrote a long time ago and say, "What was I thinking?" it's in response to how I said something, not what I was trying to say. I don't ever think, "This conflict is really exaggerated and the main character gets upset over nothing." I think, "I didn't describe the conflict and the characters' motivations well enough for an outsider to understand, possibly because I didn't fully understand them at the time. Now that I've been away from the situation, I'm closer to being an outsider myself and know how to communicate the same idea more clearly to outside readers."
In any case, what matters is how a person feels right now. It's both condescending and invalidating to tell them that something is a non-issue because it won't matter as much later on. Time may be your doctor, but it's not everyone's, and it's certainly not mine.