Why was the elder scrolls IV of oblivion changed from Teen rating to Mature

The original version of "The Elder Scrolls IV: Oblivion" did come out rated "T." Oblivion was almost crossing the line of a 'Mature rating' with content of: Violence, Blood and Gore, Sexual Themes, Language, and Use of Alcohol. When the game first came out for PC and Xbox 360, it was a best-seller. After it had been out for a while, PC hackers found out that they could hack the game and were able to access a "Locked-Out" art file which allowed the user to play the game with a topless female character due to the topless skin that they had found. Because ESRB had found out, they recalled all the of the Oblivion games worldwide and reprinted the label of them as "Mature (17+)." Now, the game labels say:

Mature (17+)
Violence
Blood and Gore
Sexual Themes
Language
Use of Alcohol
Nudity