My uses, as an IT manager:
note taking in meetings with OneNote
IT Manager that takes notes? Interesting.
reviewing documents (Word/Excel/PDF)
For every Manager that reviews documents, there are a 100+ business users that create and edit them. Very painful on a tablet, even a Surface Pro.
presenting (PowerPoint)
Again, a small fraction of business users.
email (Outlook or Mail)
Very painful without a real mouse and keyboard, you can attach them to a tablet, but that's make it more expensive and more cumbersome than a desktop at a third of the price.
web browsing
Again, painful on Windows*+ versions of the OS.
cloud storage (OneDrive)
again, this is far better on laptops and desktops with proper network cards.
Remote Desktop (Citrix Reciever)
entertainment on airplanes: video, ebooks
A 12" device is more of a hindrance for these use cases. On a tablet 10" form factor like the iPad would've been ideal.