Disney Games (that's what they're called now, they've changed their name AGAIN), were just being pricks when they didn't release the extra multiplayer maps for Evolution on the PC. It would have required virtually no effort on their part. It was literally as simple as clicking a different compile option in the Unreal 3 map editor, and then paying Microsoft to put them on GFWL as a DLC download.
Personally, I don't care because I don't like Evolution anyway. But it was a rotten thing to do, for those who wanted those maps.
At that time, a lot of studios and publishers were of the mindset that it wasn't worth investing any extra time or effort in PC games. Because these people were (and still are) greedy.
But now with all the evidence that PC gaming is going nowhere, and in fact exploding (e.g. over 7 million active accounts online at once on Steam
in December, a new record on ANY platform, consoles included), those same publishers are quickly changing their attitudes.
They've clued in to the fact that too much money was being left on the table. And then add in the fact that playing the latest games on a new PC has just become more affordable than ever with AMD's new Kaveri APU (combined CPU/GPU in one) . . .
I think that you can expect, with the next Tron game, that the PC version will actually be treated better than Evolution was. Though it probably won't be made by Disney itself (or one of their studio subsidiaries). Disney has - wisely - given up on making games themselves, for the most part.