The reason? Mike Downey says:
PDF support will be completely available in Apollo, via the Reader
That’s unfortunate, because no one installs (or at least, wants to install) Adobe Reader on a Mac.
Your average user opens their shiney new Mac and opens an email with a PDF attachment and can’t even tell the difference between whether it’s a PDF or an HTML email. Apple have made it transparent. The same goes for browsing to a PDF in Safari - you don’t launch a different application or get a crazy array of zoom, select and print buttons suddenly appear inside your browser chrome, the PDF displays inline just like any other page.
So what’s going to happen when a Mac user opens up “TPS Reports.app” (built using Apollo) which requires PDF support? There’s going to be a big what-the-fuck moment when they’re asked to install some unknown software called Reader, that’s what’s going to happen.
Is there a solution? I hope so. If Adobe can use Quartz 2D, we’re laughing. For any other fancy schmance stuff beyond the scope of the PDF 1.5 standard, use Adobe Reader.