What they should add in Minecraft is Bandits, ghosts, and Volcanoes.

Bandits would kill, steal, and grief villages, villagers.... and also your house. Every 3 kills a bandit will rank up. The more they rank the harder they will be, better things will be dropped when killed, and the more xp you will get. You can find bandit forts randomly in the plains and spruce bioms. The forts will have loot, lots of bandits, and traps. Bandits would look like a Steve but more hairy, blood and scars, different ripped clothes, and wears different armor depending on their rank. Bandits will have 80% chance of dropping 4-5 iron, 60% 3-6 gold, 15% 1-3 emeralds, and 25% 2-3 diamond (Good way of getting rich :D.)

Ghosts look like Steve but a little clear and a little white. There are 3 types of ghosts. Miner ghost- Peaceful until hit, when killed drops an iron pickaxe and what ever they mined before the died. Hunter ghost- Always harmful, when near it you will hear odd whispers and when its killed it drops meat, arrows, and a bow. Sick ghost- Always harmful, runs toward you and makes you poisoned and blind until you kill him, when near it it will make yelling sounds, drops nothing when killed.

Volcanoes spawn any were and look like a regular mountain. It will have a chance of erupting every 120-180 Minecraft days (Sounds like a lot but it isn't) and has 5.5% chance of spawning. When it erupts you will hear about 30 TNT exploding and your screen will start shaking. You can't go in the crater of the volcano, even with fire resistant potion active, without burning to death. When a volcano erupts, lava, obsidian, and cobblestone will shoot out. If you try to burn out lava (magma) that's in the volcano, it will evaporate however, the lava that comes out, you can burn it out like normal. When lava is out of the volcano for 5 days... it will turn into nothing or cobblestone. They will be about 15 blocks high minimum and about 65 blocks high maximum.