A two mana flyer is a great creature to play early in the game as it is likely to get in for a fair amount of damage or eat a removal spell out of an opponent's hand
The short version is that there's a cap on the value of the cards in a Magic set while it is in print, because if the cards in the set ever end up being worth so much that it's profitable to open a sealed booster box, people will open boxes, increasing supply and driving down prices
While it is fun to build a colorless deck with The Aetherspark as the commander, it fits better into a deck with large creatures and expensive spells, supporting the deck's mana base without restricting it to exclusively colorless cards
this deck is mainly on using half of light and dark monsters
If X is between 2 and 4, youd rather draw a bunch of cards, but if you can get to an X of 6 or greater, then its time to make somebody else draw 64 and probably lose the game