why are the NPCs in escort quests suicidal?

why are the NPCs i'm supposed to escort so passionate about charging head first into a group of enemies that "I" struggle against?
Arent they supposed to be weak and scared?

They are desperate to get to

They are desperate to get to their destination. You can tell them (once) to stay behind by right clicking on them, and selecting "give order". This is in Beta 19, however they don't stay there too long (10 turns maybe less?), and you can only do it once.

Actaully you can do it as

Actaully you can do it as many times as you wish but there is a timer between them

To make game sweeter

NPCs with instinct of self-preservation are too bizzare for roguelike world where all rotates around stupid deaths :) You can often stay on their way and they won't move, though.

Adventurers Too

These guys aren't charging in to die, they are charging in to make sure you don't steal all their kills and get all the good loot. They may be tired, injured, and retired but those instincts don't go away. They don't see a troll horde, they see a bunch of xp pinatas and who can resist a pinata?