There are many benefits to exclusivity.
Why don't people get this through their thick skulls.
Exclusivity can improve sales by quite a bit despite being on a smaller user base.

It isn't about satisfying playstation fans, it is about making the most profit possible.  150k extra units may cover the cost of releasing FFXIII in Japan (in fact, it almost certainly would), but there is the question of delaying the game.

Perhaps Microsoft wasn't willing to pay for multiplat FF13 in Japan and SE wasn't willing to throw it in for free.  It might come there eventually.

FF13 wouldn't sell fewer units in Japan by staying exclusive.  I don't see how you could possibly argue that.  It would certainly sell more units if it was on both platforms.

The 360 is the future of HD consoles this generation and S-E sees that.  However, this is only true for Europe and America. Japan is still up for grabs as no HD consoles have sold well there yet.

Enlighten me.

Eh, not really. Flagship exclusives do receive more media attention and hype resulting in increased sales, other games not so much.

How does it have to do with localization costs?  You have the game ported to the 360 in America and you have it localized for Japan already.  Both the porting efforts and the localization efforts will cost about the same whether it was released on the 360 in Japan or not.  Either way you already have to:

(1) port the game to the 360 hardware

(2) localize the game for Japan and the US and also for various countries in Europe.

Square probably has some kind of deal with Sony regarding Japan and FF series, who knows.

If it indeed stays exclusive to PS3, expect a surge in HW sales of the likes that will make the release of MGS4 in Japan something like: "nothing important happened today" @_@

In any Bussiness, time = money.

SE probably decided that the time it takes to make a 360 port of the game (about 4-6 month?) is not worth the financial lost it will suffer from the delay.

Having the game come 6 month late to Japan would probably make even less money than it would on a simultaneous launch, weighing their option, they decided that the best action was to gain a bit of browny points from PS fans in Japan and maintain the exclusivity.

SE like all company needs to look at the bottom line, but sometimes time is worth more than increase sales.

theres no point because 360 has a small install base in japan and the game is almost finished in completion.

btw, whoever keeps saying that final fantasy 13 is being made on pc and ported to ps3 is a complete idiot.

 That have all flopped, and they are probably thinking, if we release FF XIII on the 360, our games may lose popularity, like every single RPG released on the 360 in japan.

seriously it sounds more stupid release exclusive games on the 360 and in japan first.