I think search has been deprecated in general because it gives the user too much control over the output. Through search, people can quickly find what they are looking for, which is bad. The goal has instead become to feed people tiny scraps and hints of what they're looking for, while leading them on a long trip past any number of sponsors to where the thing they're looking for might be.

I have to assume that Outlook email searches have already been set up to have ads injected into them, when/if one day Microsoft decides to flip the switch. Actually, I'm so out of touch with Windows they might already be doing this.