So when you stared at endermen (place crosshair on them and don't move it) Endermen used to stare back at the player and stand still while playing the creepy scream sound. (at least in old Java-Minecraft versions)
They don't do that anymore, now they just start running and attacking immediately.
HOW TO REPRODUCE;
1. Be in survival mode
2. Stare at an enderman (place your crosshair on it)
3. Notice that Enderman doesn't freeze and stare back, but instead just starts immediately running at you.