I think Namco just figured out that most of their fanbase is also on Sony and a lot of their potential fanbase is there without Microsoft. I actually remember them specifically saying that about the Tales series.
I wouldn't expect a PC version, though, even if it was an easy port. PCs aren't really a common thing for people to have and play games on in Japan, as I understand it. The only real gaming scene on PC is the doujin game scene. PC gaming is so vague and unknown in Japan that a lot of people, even those who work in the game industry, think Steam is a PC game piracy platform. Recent successes are starting to correct that, but it's still all western success. I doubt we'll see a shift to PC gaming in Japan any time soon, if ever.