When Microsoft decided to embed its Cortana digital assistant into Windows 10, the original plan was to keep it out-of-the-way, nestled in the system tray. However, before the OS' release, the Redmond giant decided to push it to the taskbar, to the right of the Start menu, which was done to encourage discovery. At this point, many know what Cortana is, so it appears Microsoft is planning to give the talkative assistant a notice of eviction from its current residence and court it with a good rate in system tray city.
Because Microsoft originally chose to put Cortana close to the Start menu, many users have complained that it's in the way. So it should come as no surprise that a lot of Windows 10 users have gone through the effort to disable Cortana, or at least remove it from that location. Once it's removed, it's essentially out of mind, and rarely (or never) used.
Here's something worth noting: according to Microsoft, Cortana's usage is high, but how that's determined is a little sketchy. If you hit the Windows key and search for a term, for example, you're automatically bundled into the group of actual Cortana users. The same applies if you are using Edge and Cortana pops-up in the URL bar. Given this, even if you don't think you use Cortana, you apparently do.
Nonetheless, with Cortana placed in the system tray rather than the taskbar, fewer people are likely to disable it, because it won't be quite so in the way. But that assumes that the AI isn't going to evolve to become chattier, and continue to pop-up when the user doesn't intend for it to happen.
One aspect of the upcoming Cortana move that does sound really good is that Microsoft is evolving the AI to handle actual conversations better, a la Apple's Siri and Google's Allo. This is something that's a long time coming, and can only help with user adoption - even if this type of feature sounds best used on a phone, rather than a desktop or laptop.