If you want the honest truth...
This is not Squares fault - Sony backed them into a corner to force them to make it multi-plat. The Playstation 3 had abysmal sales during its debut, and for the most part of 2007-2008.
Because of that, business strategies can and will change. Square is in the business to make money. You can only make money by selling to the largest, or best (in terms of software adoption) consumers possible.
Look at their gamble with Dragon Quest IX on the Nintendo DS. Dragon Quest is one of their flagship titles, and it went to the weakest hardware of this entire generation. Yet despite that, its paid off in spades for Square, as IX has broken any and every record that could be put forth.
Likewise, Square had to go the path of ensuring sales. I've said it before: Put yourselves as the CEO of Square. Either you keep exclusivity on a console that may is having an abysmal time at hardware and software sales, or you go multi-plat and try to cover your losses with this American-made console that has sold better than the PS3.
Did it hurt the quality of XIII? That is something we will debate until the cows come home. However, as much as you want to be a fan of exclusivity, you must understand the market. Square bailed on Nintendo for economic reasons. Why should you assume they have some sort of favoritism to a company, and not favoritism to their workers and shareholders which have to eat?
Like a few other (smart) posters have said, these companies don't make games to be the most jaw-dropping, OMGFANSERVICEZ games unless they can viably state that the product will make them money. Because of that, you aren't always going to be the happiest with their decision.
And for the record, no Playstation fan has the right to complain about FINAL FANTASY jumping ship. I bought a friggin' N64 because of Final Fantasy VII. Crap happens. Deal with it, or don't buy a console until you know it has the titles that you want on it.
Back from the dead, I'm afraid.