Switching control of a creature doesnt cause it to leave or re-enter the battlefield
Getting back a board full of Dreadhorde Arcanists, Young Pyromancers, Kroxa, Titan of Death's Hunger, and friends in the mid- to late game seems pretty powerful
Oh, and after you do all that setup, how sad are you going to be when your opponent just plays a Benja - Guardian of the Dragon Gem and blows everything up
All in all they are great cards, they are pretty skill intensive as lands go and offer lots of choices for deck design as well as in game, they are a lovely design which improves magic and are not of a power level where they are always an auto include
Izou is an accessible card, perfect for beginners or collectors aiming to complete the secondary character lineup from the early expansions