Originally posted by Polonius Ulf:

The root set is resistant to pierce and poison. In the swamps, Draugr archers have a hell of a kick, and of course poison is your other big enemy. Root armor adds 15 points to your archery skill level and allows you to be more agile than bronze or iron armor.

Because of the way it looks, I think root armor should also boost sneaking.

Yeah, honestly every light set should boost sneaking somewhat imo.
I think if the root set did that I would definitely think it would be worth sacrificing the armour stats for it.