I think the fact that few developers enjoy using Outlook is causing you to overgeneralize. Most people who don't care about things like whether their email is in mbox format, or who don't want to learn how to use Mutt or notmuch, find Outlook surprisingly easy to use and powerful.
I poked around on outlook.com, and I don't see anything particularly innovative, other than it looks and works nearly exactly like Outlook 2013. But I wouldn't assume its lack of anything novel dooms it to obscurity, either. Outlook, unlike Notes, is a positive brand-name in some circles. I wouldn't be surprised to see this get a relatively large amount of traction right off the bat.
I didn't realize this myself, either, until I started working at an employer that uses the Google Apps stack for all things corporate.
One complaint I heard was the lack of sorting features (sorting your inbox by subject, sender, etc.) which also drives me nuts when I use Gmail on my personal account.
The same way having a desk is expected.
People that use software to do other things often aren't interested in how wonderful the software is, provided it stays out of their way and allows them to get stuff done in a way that they expect.
The marketplace for a beautiful desk is much smaller than the market for a functional, yet ugly, desk, especially if that nice desk can't fit through the door of my office without me removing the frame, etc.