One of the complaints about Windows Runtime (RT) has been that it does not make anyone truly and fully happy. Enterprise users don’t get legacy support because RT is powered by ARM architecture chips instead of the X86 architecture prevalent on Desktops and Laptops. Consumers have a smaller app store that is still missing some of the big name apps.

(Despite the numbers advertising, do we really need a 1,000 flashlight apps? Quality over quantity is really what is important when deciding on an ecosystem. Plus, does it have the major apps that you use?)

So on multiple fronts, Microsoft has tried to augment the app library (promotions and incentives to developers, building some apps themselves), while offering more features that enterprises want. This is where Outlook comes into play. Some organizations may not have even considered RT simply because it does not offer Outlook. Problem solved.

http://www.pcworld.com/article/2040800/microsoft-to-add-outlook-to-windows-rt.html