This might just be because it's difficult to build a cascade-themed deck, especially without some of the expensive big-hitters like Rashmi, Eternities Crafter and Maelstrom Wanderer (which were likely too new and too expensive for Commander 2016 ), but the end result is a deck that is vaguely cascade-ish but not a good cascade deck by any stretch
Being the best in Lorcana doesn't necessarily mean the most powerful, as a card's usefulness relies on its power and effects being appropriate for the cost
While this is a flavorful fit given shes the games antagonist, this effect does dampen her effectiveness somewhat
Summoning sickness applies no matter if it was cast from your hand or from exile
The card may also have some surface damage such as a small amount of writing on the front or back
Fantastic, The Sentry, Quicksilver, and Doctor Doom