I remember grade school. Cindy had a booger hanging out her nose. You didn't say anything because Cindy was your friend and you didn't want people to laugh at her because she wouldn't like you anymore. Or you didn't like Cindy so you made sure the whole class knew so they would laugh at her and you would be popular.
Children see everything as about their feelings. You don't really say or do anything beyond the scope of how it effects YOU.
Then you grow up and realize everyone sees the booger in Cindy's nose. You want to say something because it will probably be embarrassing when she realizes she went to a big meeting with booger hanging out of her nose. You worry about how to word it, should you say anything, what if it still hurts her feelings and she is mad at you. You care about her feelings but are still close enough to youth to wonder is it best to tell her about the booger.
Young adults care about other's feelings but still remember getting burned in grade school.
Then you get older and realize that all the time it took for you to debate Cindy's booger she went into the meeting. Her new boss was a germaphobe and because of the errant booger she didn't get a promotion. You realize that because of your fears your friend was hurt so the next time she has a booger hanging out her nose you say hey, let me get you a tissue, you have a booger right there!
It is not that when you get older you get cranky or mean, it is that you realize trying to protect your own feelings can actually hurt your friends. You also realize that your friends are mature enough to realize you weren't trying to get the class to laugh at them, you just don't want to freak out their germaphobe boss.
You realize all that grade school stuff was self centered.
Then there are some that just never mature and call us old farts cranky when they aren't much younger. We aren't cranky, we just don't play games anymore, we are real.