1. If you have the Japanese PC re-release, it's likely you can copy the voice files in from there. People have also been talking about a fan patch.

2. Only reason they don't have the Japanese voices is because of licensing/contract issues regarding the Japanese voicework. XSEED really wanted the Japanese voices but couldn't get them.

3. The Japanese voicework was not present in the original 2004 Japanese PC release.

4. The voicework consists of language-less battle grunts and a few calling-your-attack lines, totalling about ten lines per character. None of the main text is voiced.

5. The English voicework can be turned off.

I even put emphasis on this that XSEED did want the Japanese voices in the game.

To give another reminder to the people who have said that they want to vote with their wallets and use this as an example to show companies that they won't buy games without Japanese voiceovers: you're punishing a publisher for something that they cannot control.

They can't change the contract and licensing system in Japan regarding voice acting. As a result, not buying the game simply gives a bigger, simpler, and more destructive message: you don't want JRPGs.

Please remember this.

Thanks.

EDIT:
Here's the exact quote from Tom regarding this issue:
http://www.neogaf.com/forum/showpost.php?p=50395479&postcount=1