Zombie Pigmen: All Risk, No Reward

 Zombie Pigmen are unique monsters, because they only attack you if you attack them first, and they react in numbers. This creates a really large risk that, if you hit a Zombie Pigman, you will be under heavy attack. The problem is that there is not a worthwhile enough reward to balance this risk out. A small amount of gold per Zombie Pigman killed simply is not worth the risk.

An obvious fix to this would be to give Zombie Pigmen better drops and maybe even a new, unique drop, but that just makes Zombie Pigmen farms better, so it doesn't do much to incentivize actual combat. A much better way to fix this would be to make Zombie Pigman attack the new Pigman trader mob that people keep suggesting. This would force player to assess the reward of what the Pigman has to offer verses the risk of angering all of those scary Zombie Pigmen.

Whatever Mojang does to fix this risk/reward imbalance, it should probably be well interwoven with more of a nether update, so that it feels natural.