The reason this happens is because cards don't retain any knowledge of their past when exiled, and so default back to the untransformed state when they re-enter the battlefield.
The effect is extremely strong, but it definitely doesn't fit into just any decklist
Cards that are almost always worth grading: Vintage base set cards (1999 Pokemon Base Set, original Magic: The Gathering) First edition holofoils from any popular set Secret Rare and alt-art cards from modern sets worth $80+ raw Rookie cards of major sports stars 1st print run cards with strong collector demand Which Grading Company Should You Choose
This has led to some of the cards becoming true cult objects, worthy of being kept by a few, and has sometimes led to a simple cardboard card becoming something more
Note that there are no brakes here like once a turn and this does count as casting from exile for those triggers
Having scry cards in your deck improves the effectiveness of your other cards more so than other mechanics