"I think you’re all either missing the point or hitting it on the head. Yes, Avacyn dies to a morbid Tragic Slip. Yes, she can get O-Ringed. Yes, she can get Mana Leaked, Vapor Snagged,Phantasmal Imaged, Mind Controlled, what-have-you. Whatever, we get it! She can be dealt with! So can 99.9% of all the other seemingly-broken cards/combos out there in MTG. Wurmcoil is easily dealt with, and so are Titans, Elesh Norn, heck, even Thrun can die (Black Sun’s Zenith). Frak it, it seems like the entire Magic community is becoming Spike these days. They’re in it to win big, and this otherwise really cool card is ash on the wind to them.
I think what I’m trying to say is, all creatures, planeswalkers, etc. have their weaknesses, but we shouldn’t easily discard it because we take one look at it and say “Durr hurr, it won’t see standard play, what a junk mythic. Would be cool in Commander, tho, durr hurr.” That is narrow-minded thinking, even for all the good reasons we can make for it being bad (and there are plenty). Magic isn’t just about competing and tourneys, people! It’s also about flavor, story, constructing fun decks (not just ones that “win tourneys”), playing a good game where there are no stakes involved, and having fun. That’s my take on it.” -AOC on Gatheringmagic.com