Because Cloudkin Seer is a flying, 2/1 Visionary, and that's a strong card
They will be forced to deal with little Budew, but unable to use any Item cards
In the main set, there are a few legendary creatures that seem built for Commander - there's a cycle of three color commanders as well as a few two-colored and mono-colored commanders
Pawn of Ulamog works in the same strategies as Black Market, though a bit more slowly since it only triggers when your own creatures die
Demigod packs are more common than god packs and represent a significant hit even if they fall short of the full god pack experience
One card sets itself apart as the sole survivor of a Mewtwo takeover, and that card features a character that you've likely never even heard of, until now