Phil adds on the blog posting that they "already owe Microsoft a LOT of money for the privilege of being on their platform." Polytron apparently has to pay Microsoft for being an exclusive on Xbox Live Arcade.
As for the patch, Phil states that it "fixes almost everything that's been wrong with the game since launch." Examples given were issues such as the framerate, loading, and death loops. "For 99% of people, it makes Fez a better game."
The patch was originally pulled as it would delete people's save file without notice. This issue apparently only plagues about 1% of players, and according to Microsoft the patch issue happens so rarely that it's considered "good enough."
Phil apologized to anyone that has or will be affected by the patch bug:
To the less-than-1% who are getting screwed, we sincerely apologize. We know this hurts you the most, because you’re the ones who put the most times into the game. And this breaks our hearts. We hope you dont think back on your time spent in FEZ as a total waste.
A truly shitty situation all around. There is some good news finally, as the Polytron Twitter just mentioned that the Xbox Live Arcade exclusivity will be up on "only a few months." Not much longer until the Steam release now.
WE’RE NOT GOING TO PATCH THE PATCH [Polytron]
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