Like most Magic: The Gathering cards, the value of Corroding Dragonstorm depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Tarkir: Dragonstorm)
There was some chance that a combination of art and explaining it to people would solve the confusion, but we only have that option with our most enfranchised players
Honestly, In casual commander 1 card out of 99 doesn't impact the game
With creature-heavy decks, more card draw is always crucial because you need to be able to recover from board wipes
Unfair I think for any level of Commander that isnt cEDH, what kind of interaction you choose to play boils down to asking yourself, Is my opponent doing something fair? Graveyard decks are the perfect example to look at for this, as they are fundamentally breaking the rules. Whenever a game action is achieved through spending less mana than it usually should, its considered to be breaking the rules. Similarly, when a game action rewards you with more card advantage, mana production or other resources in greater abundance than the going rate, its also considered to be breaking the rules. Breaking parity in this way whether through a play as powerful as reanimating Griselbrand or something as innocuous as flickering a morph for less mana than the morph cost is what helps us win a game of Magic
