Like people mention above, the hardware isn't the only impediment; Apple's control is what helps them a lot with this. Desktop Windows' support for DPI scaling is anemic at best, and this is only partially fixed in Windows 8 by having ad-hoc dimensions per-device, or on PCs just "big" vs. "really big" mode.
FYI, Outlook still doesn't have IMAP support [1]. It does POP3, SMTP (of course), and full Exchange ActiveSync. For now, this is a dealbreaker for me; I'm thinking about trying out Outlook for my basic data/web/cloud, but really only because of Gmail's shitty push experience with my devices.