Are you talking "why do people still have their original first Gen Surface RT?" ...or "why do people still use Windows RT in general"??? Because if the latter, I can assure you RT is not dead, but quite the opposite. RT is the future! It's the OS most likely to be merged with Windows Phone and it's all we're going to need in the near future where the desktop isn't needed (or wanted in a mobile/touch interface). Windows RT has come a long way. 8.1 brought many improvements along with the new gen ARM hardware.
I won a Surface 2 with the Music Kit (Win RT 8.1) and I absolutely love it! It does everything I want it to do right out of the box. I can watch all my HD movies/videos from any shared folder on any pc on my network (even .mkv files with an app), listen to all my music, view any website with ie11, read and compose all my emails, and open and edit any office documents with Outlook, Onenote and the Office RT apps (Word, Excel, Powerpoint)
I can also control all the other PCs on my network via Desktop Remote or the PC Remote app flawlessly.
Uhmm what else is there? Running desktop legacy x86 applications? ...Got news for ya, you can't run those legacy applications on an iPad either!
Windows RT is a perfect tablet OS! Fantastic!