"These Heroes are very, very, very, very, very, very rare."
For any player, it only means that the time he gotta spend to get the card is long. Anyone can still get it.
I like those cards, the designs (Obama, lol
), the ideas for the powers (clock a bit too powerful though, yes)... but we either need at least 4 heroes per element, either no hero. A lonely hero with his power grants big advantage to a certain type of strategy, not all strategies for a given element. Anyway, with 1 hero only per deck, you must choose what type of strategy your deck is going around (to optimize it with the hero), instead of having several possible strategies in 1 deck.
So... no. Easier & sure decision not to get heroes for Elements. We could still underpower some of those cards to make excellent "normal" ones!