Well... whatever the case is, the politics from this press release might be something else if true.
If I'm going to make another blank statement from the evidence before me... (the shift to DS being the "main" platform, the releases for the PSP and PS2, and the fact that TOS2 might have been a PS2 game at first...)
At first, it seems like Bandai-Namco were developing these games to show that they believed that Sony would win Japan.
However, now that it's clear to them that the PS3 and PSP won't be a major force in Japan, they've basically shifted the new Tales games onto Nintendo platforms in order to try to win support and rapport from Nintendo and their fans in this generation.
Basically Bandai-Namco is saying, "Developing for non-Nintendo platforms is a lost cause! Head to where the money is!"
...And no more random speculation from me. Because if a Tales for PS3/360 is announced soon, my theory will probably be useless.
Edit: I lied... I have one more piece that I forgot to add.
It's actually clever the way they did this. If you see increasing support for Wii in the future from Bandai-Namco (e.g. more new Tales of games), this talk of DS being the "main" platform was just a way to weasel out of announcing who would win the home console war.
Right now, they would probably have a hard time explaining to Sony why they have chosen the Wii as the main platform, since it's a bit early. (It won't go over well if they just tell them: "well, you're losing.")
However, by choosing the DS, they can claim that for financial reasons, not supporting the DS would be suicide.