I would wager someone with an MBA got their knickers in a twist about "PC being the most pirated platform," did that thing like in cartoons where the dollar signs in their eyes turn into cents signs instead, and decided to just 86 the whole thing because they were deathly afraid that a couple hundred people who never in a million years would have paid for it in the first place would download it off of Kazaa or whatever was popular back then instead of giving Rockstar any money.

Just a guess.