"What did Capcom do wrong with Okami? What did Sega do wrong with Valkyria Chronicles? What did EA do wrong with Mirror's Edge and Dead Space? What did Ubisoft do with wrong with Prince of Persia? What did Epic/Midway do wrong with Unreal Tournament 3?"
What did you do assuming all those games didn't flaws in execution, marketing, or other factors?
Flaws in exectution? Not every game is perfect. Uncharted had its' flaws, but it was still a good game. MadWorld has its' flaws but it's still a good game. Marketing? I don't know about you, but when those games were initially coming out, I saw a good amount of commercial for them. And with viral marketing becoming even more popular, you can't say they weren't heavily advertised. Other factors? Time constraints, no money at the time, etc. are all things that could be factored in, but they are not absolutes because we don't know the cause behind every situation. Otherwise we could all say "Nobody bought game X because they were all broke when it came out"