Not just because they chuck a whole pile of new cards at you (which they certainly do) but because while MTG has been one of the best card games for the last three decades, the Commander format is a particular favorite among players
Just having an Overrun or two available is pretty strong, and early in the game, you can defend yourself from spot removal thanks to the regenerate ability
Suddenly, the best card on the battlefield is yours
(2017-04-18) If you're casting a split card, only the mana value of the half you're casting is compared to the number of time counters on As Foretold
Less-experienced players will play a creature with a death trigger and then just play it as if it was a vanilla creature, ignoring the death trigger
Put Zack Fair's counters on that creature and attach an Equipment that was attached to Zack Fair to that creature