I know this is old, but Hide in Shadows was a necessary in Eschalon Book I if you wanted to play any type not known for direct confrontation.
I like to play Ranger types . . . always, and so I often pick skills they'd have, such as the ability to sneak up on prey, which is essentially what 'move silent' and 'hide in shadows' indeed is. People think of these as rogue or criminal skills, but they aren't. They're hunter's skills that criminals use for nefarious purposes.
Anyway, in Book I, if you wanted to be that type, it was absolutely necessary to have hide in shadows, but not really move silent. Truth be told, I often got annoyed when enemies didn't come towards me because it meant I had to move out from hiding or waste arrows. Move silent didn't help attract their attention, and in fact makes it harder to attract their attention.
Oh, the benefit was that the enemies would walk around you without striking at you, which meant you swing your sword and miss or do no damage a bazillion times without getting hit back, and often that's how long it took to actually get a strike that does damage. It was frustrating. At times, it seemed like I swung that sword 20 to 40 times before it actually did any damage. I would just sit there with my hand on my face relaxing my head, and click and click and click and . . . and click and then damage finally. They always have a chance of finding you once you do damage, and they attack. Then you step onto an adjacent square, typically up against a wall, and you go back into hiding. Hide in shadows allowed me to actually finish the game because even at citadel level, I still couldn't take on the more powerful enemies in a direct one-on-one fight. A single Taurax would still beat me in a fair fight. But using hide in shadows . . . read below.
One instance was epic. I had about 7 goblins and 5 Taurax all following me like the computerized marching sounds of an army, and couldn't even take on a single Taurax in a direct fight, much less 5 and 7 goblins . . . and then the sun went down. I disappeared into the night as I walked (hide in shadows was high enough by that time to disappear at any location so long as it was the dead of night). I buffed with some spells and even before the moon hit midnight I had slaughtered each and every one of them. I earned a name that night that no goblin dares speak for fear I may hear it slaughter them like as an invisible phantom. I don't know what that name is, because like I said, they dare not speak it. Granted, that was at the time that I was ready to take down the Citadel, but still, it was movie-worthy epic.
I don't know about Book II. I'm trying that one now, but the first few levels of hide in shadows seems to only work when you're not already seen. So far I can't just disappear when I'm already seen like I could in Book I, so it's been pretty useless to me so far.