From Mark Rosewater's Tumblr: the0uroboros asked: How in the same set can we have a hexproof, unsacrificable(not a word) creature AND a land that makes it uncounterable. How does this lead to interactive play? I believe I’m able to play my creature and you have to deal with it is much more interactive than you counter my creature.
MaRo: One of the classic R&D stories happened during a Scars of Mirrodin draft. Erik Lauer was sitting to my right (meaning that he passed to me in the first and third packs). At the end of the draft, Erik was upset because I was in his colors (black-green). He said, "Didn't you see the signals? I went into black-green in pack one." I replied, "Didn't you see my signals? I started drafting infect six drafts ago."