I think the reason why Uematsu didn't compose FFX-2 wasn't because of FFXI, but because he was busy with FF12. FF composer Nobuo Uematsu and FFT composer Hitoshi Sakimoto are combining their efforts to make FF12 a new, grandiose and powerful soundtrack. From what I've heard, FFX-2's music still suits the game very well, and there are some orchestral and emotional songs in FFX-2 soundtrack, especially "Until the Day We Meet Again", "Epilogue - Reunion" and "1000 Words - Orchestral".