"Has the world changed" is too general to answer. Of course, technology has changed, a lot. It's changed the way most people live their lives.
But human nature remains the same. It was never warm and fuzzy. Anyone who remembers their childhood that way is probably thinking about their happy childhood, being loved and protected. (Not that everyone had that, either.) But the warm and fuzzy feelings came from their personal experiences in their little corner of the world. It doesn't mean the world as a whole was any better.
Just a look at the newspaper headlines of our childhood days should be enough to convince us. In my own childhood (which was personally a happy one), the world was experiencing the Holocaust, WW2, lynchings, zero civil rights in this country for anyone other than White males, kidnappings, sex slavery, horrendous punishments for kids, polio and other horrible diseases that are gone now, and a recent Depression that ruined millions of lives and brought many people to the brink of starvation.
IMO, anyone who thinks everything was hunky-dory back in the days when they were children is looking through rose-colored glasses. Maybe I'm a pollyanna, but I think that in general, "the world" has slightly improved. It's two steps forward, one step back.