Except they dont because many of the critical cards are mythics?
It's a slow Saturday and I'm bored.
EMA mythics
Card-price today/price during SOI release
Force of Will-110/80 +30
Mana Crypt-93/166 -73
Karakas-75/155 -80
Jace-70/92 -22
Vampiric Tutor-28/31 -3
Natural Order-26/33 -6
Sneak Attack-26/43 -17
Dack Fayden-20/35 -15
Chrom Mox-15/15 +-0
Maelstrom Wanderer-12/25 -13
Argothian Enchantress-9/14 -5
Necropotence-8/9 -1
Balance-4/1 +3
Worldgorger Dragon-2/3 -1
Sphinx of the Steel Wind-2/1 +1
Most cards saw a decent price drop while maintaining some value. Some saw a few dollar difference. There are two cards with at least $70 dropped price. FoW is a unique beast because it's a demanding 4 of and that new art is sweet, so the price actually increased.
Again, even if the prices didn't drop by much, there are more circulation of these cards now. These cards and most of the modern staples we want reprinted would honestly be too busted to be reprinted in standard. So I'm fine with the master sets for the most part, even if I opened pretty crappy with the MM15 set. ;(
*edit
Tcgplayers' response and changes to the buyouts.
http://store.tcgplayer.com/help/buyoutresponse