He served up a lemur instead, resulting in the cuddliest, flesh-gnawing furry creature ever devised for Magic
Elf decks already flood the board with mana dorks, lords, and combo pieces, so having a Commander who can protect those Creatures from destroy effects gives the deck a lot of staying power
If they cant, they sacrifice an attacking creature. You can also lose two loyalty to accept an offer and a condition, which is basically one good thing and one bad thing from a pool of good and bad things
The Battlemages were simpler, as they were "virtual vanillas," meaning they had effects when you played them but were just 2/2 creatures for the remaining turns, so they went into Planeshift
They are simply different options that can be mixed, swapped, or adjusted depending on your preferred strategy, playstyle, and the cards you currently have available