http://kotaku.com/5666353/final-fantasy-xiii-developers-couldnt-cater-to-a-western-audience
Testing should of been done much earlier in development and fyi Sqyare stop hiring idiots to write your scripts."Linearity and command-based battles were two of the features being perceived negatively. This was something that the team was very conscious about, and there were concerns about whether JRPGs would still be accepted in the West. Because Final Fantasy XIII's mission was to succeed worldwide, we could not ignore this issue, as we felt it could deeply affect the future of the franchise."
So focus testing sessions were held in Western markets. And they achieved...well, nothing.
"Unfortunately, we were already quite far along in development, and knew it would be too late to implement most of the feedback from the player test sessions. Even so, we still signed up for the opportunity, as this would be our only chance before the game's release to see how Western players would respond to all that we had been working on."