It already takes long enough to finish a game of Commander without one player intentionally slowing things down and restricting resources
Technically, there are no sideboards in EDH, so cards that use them don't work
It looks like a dragon payoff, but its a huge liability when your opponents copy or reanimate it, and the payoff isnt even that great when that doesnt happen (compare to Dragonlord Kolaghan)
Bushi Tenderfoot / Kenzo the Hardhearted Bushi Tenderfoot has a similar activation ability to the last two, and the interestingness of this is whats pumped it up a place or two
If you have enough lands in your hand, this can result swift and massive land production
However, having it on the field enables you to cast spells as though they had Flash