That’s simply not true. No major developers are ‘ditching’ Sony. According to an article at http://www.pcgameworld.com/news/, 18 of the 200 developers planning to produce titles for the XBox “have committed to making exclusive Xbox titles to be published under the Microsoft label.” Of course they’ll develop for the XBox if Microsoft pays them to. Many development houses only produce one or two titles at a time and take publishing deals where they can get them. They’re not ‘exclusive’. They’re just small. There are a lot more than 18 developers working ‘exclusively’ on Playstation products, and without Sony footing the bill.
As for DirectX being ‘easy’ to develop with, most PC titles are using DirectX now and generally have longer production cycles than console games. In any event, the large publishers don’t care about hardware performance or ease of programming, whatever that means. They’re interested in market penetration and political necessity. Some publishers ignored the Dreamcast not because it was a bad piece of hardware, but because they thought it wouldn’t sell enough units to make development lucrative in the long term. Looks like they were right. Developers who are signing on for the XBox are doing it either be cause they think it will reach a large install base, regardless of quality, or because they have to. Personally I think it’s more of the latter. You can’t afford to give Microsoft the snub, especially if you need their support for your PC titles.