I've known about this for so long.

being inferior? comes with multi disks? throw in negative news about the xbox version, bottom line is that 360 ownes will still enjoy this game equally.

Pretty sure that's not true. I actually found a interview with Yoshinori Kitase that IGN did that proves it untrue.

Behold:

IGN: Why was Final Fantasy X the first Final Fantasy game to be given a true sequel?

Kitase: We included a short story/movie titled "Eternal Calm" in FFX International, which was released in Japan in January 2002. "Eternal Calm" showed life in Spira, after the ending of the original story in FFX. Fan reaction was larger than we expected and we decided to continue the story of Yuna and surrounding characters in a sequel.

At that time, our team was ready for a new challenge (for a new game, not a sequel) but we thought that creating a sequel to FFX would still be a challenge in a different way and so we made the decision to create a sequel.

Motomu Toriyama: FFX was a "complete" product that it made it very difficult for us to just say good-bye to it. Also, the characters were so appealing that many fans wanted to see more of them. However, what really triggered us to move forward with a sequel was the inclusion of the "Eternal Calm" in FFX International (only released in Japan); a short story that depicted the world of Spira two years after the ending of the original story.

IGN: Was it always the plan to be told in this manner? As two parts or even three-parts? Or is this the result of something that happened after the game had already been released?

Kitase: No, it wasn't planned - as mentioned in the previous answer, it was triggered by fans reaction to "Eternal Calm."

Toriyama: When we were working on FFX, there were no talks about a sequel. However, after completing FFX, we thought it would be nice to create a new story in this same world some day. Personally, I wanted to create a game where one could revisit the world and the characters - say, maybe once every two or three years. So, it was quite meaningful that we were able to do a sequel with FFX-2.

so what???

Lost Odyssey has 4 discs...

Give me sometime and I'll find you the video interview where he said that. Also, i'm curious about this one. He says that this was triggered by fan reaction to the Eternal Calm, yet that was only in the JP version. How could fan reaction be so massive for this particular international version and never was for other versions that had cut content. 

No FF game is ever "complete", he kind of contradicted himself in there.

That's the thing, though. Going by this interview it's pretty clear that FFX-2 was not cut content, and they thought it up because people reacted so strongly to Eternal Calm. They wanted a continuation to FFX, so they thought one up.

I think we can't really know. Square Enix has an incredible compression system.

The basis for the strong reaction is for JP alone, since very few fans outside japan even saw the Eternal Calm. Why do that for FFX and not for every other FF? Heck, FFXII:Zodiac Job System had a massive fan reaction as well, but did you see it coming here? Or FFX-2 Last Mission?

It had made sense if they did FFX-2 for JP alone, since it was there that the fan reaction was felt. Probably not all of the history and content of FFX-2 was cut content, but there's definetly something that was taken from the cut content of FFX, especially the Shuyin story, as that felt almost deliberately left out of FFX (after explaining that he was just a dream of the Fayth, they never explained then who was the real person that Tidus impersonated).

I'm pretty sure that's mostly because you can play it in English, Japanese, French, German and Italian.  Plus it had lots of cut scenes which take up a lot of space.  I would have been happies if it only had two voice tracks and someone would have narrated the Dreams of a Thousand Years because I only bothered to read one or two of them all the way through its still a great game though and one of my all time favorites.

Because FFX-2 was an actual game and not just an "addon".