First, it could be a huge mana ramp for the casting player , as you'll be able to attack the turn it comes into play and then tap all your land for double mana at the cost of that much damage
Several of the Moonfolk are all-star material, like Meloku the Clouded Mirror and Uyo, Silent Prophet
Its a little worse in Commander since you cant sideboard it in or play multiple copies, but protecting your team from countermagic and blue and black spells for a turn while potentially drawing a card often feels like a blowout
It just seems like it would be too much hassle, and thats not to mention everything that happens around the game
As with any Magic product, the value is partly subjective
Starting at 10 damage and adding 30 per Energy, it could easily reach one-hit knockout levels