Endermen are too lenient

Description:

Attacking an enderman in a cave does not make them persistently angry at you. They teleport away after you have hit them, which is normal, but they seem to forget who the attacker was when they teleport back, or they simply teleport to some area unknown and not fight back. (This bug would be an awesome feature, but it does not seem intended)

Steps to Reproduce:

Attack an enderman in a cave.

Expected Results:

The enderman will persistently fight you to death.

Actual Results:

The enderman is not persistent in fighting.

Remark:

This does not always happen because it depends on the cave size and where you fight the enderman (e.g. against a wall), but some endermen do this which does not seem to be intended.