That might be true. The advantage that The Coin gives you is highly dependent on the deck that you have. In that particular deck that I used in the simulations, the advantage is rather large. For a deck consisting of stronger (higher mana) cards, the advantage is much smaller. I think it's basically due to the fact that a 2-mana drop vs 1-mana drop is much stronger than a 7-mana drop vs a 6-mana drop.
Yes, sorry I was referring to his numbers in the simulator rather than in the actual game.
In the game it depends on the deck - for some decks, it's more useful than others, either due to particular mana curves, or to triggered effects (the coin counts as a spell, so can trigger cards like Gadgetzan Auctioneer or Wild Pyromancer)