One ring to role them all one ring to find them and in the darkness bind them

hugh

This item seems less like the One Ring and more like the cloaks the fellowship received in Lothlorian (in the film version). Frodo and Sam even "used" their cloaks' power to be obscured from the evil soldiers heading into Mordor. I plan to interpret this item in that respect in my games. 

Quote from ColdLogic >>

I know when I’m playing a sneaky boi I always use the topography to decide where I’m hiding. I play exclusively non roll 20. So if we are in a dungeon I may hide in a shadowy corner or at the very least break line of sight with the enemies. Incidentally I also have that wood elf feature mask if the wild, that lets you try to hide in light obscurity. Because like you, I think hiding in the middle of an open field is stupid. 

Considering that I'm ex-special forces, I'd say you're entirely wrong about hiding in "open fields". That's partly because modernity has people rather stupidly believing that "open field" is something like what they're used to seeing - a mowed lawn at a part - rather than a field of grass, sticks, flowers, rocks, and other things that actually do help people blend in when wearing proper attire.

Blending in is FAR easier than people think, assuming one knows how. For those who don't know how, it's simultaneously easier than they believe, and yet also harder than they assume depending on the context.