Interesting, because I'd say Apple characteristically look to the long-run and eschew short-term gains for long-term domination. But I digress.

I think this is for technical reasons, as well as other strategic reasons, but if we assume this has nothing to do with tech, then I'd say John Gruber has it nailed: http://daringfireball.net/2010/04/why_apple_changed_section_331

Actually, it's not just me that thinks Gruber nailed it, the media are reporting that Steve Jobs himself has pointed people to Gruber's post approvingly.

Bart.