Why is iWork not part of Apple’s cloud computing system?

I would like to ask if there are ongoing issues on Apple’s cloud computing system and document application? I recently found out that documents done via Pages may be shared (in the control panel) using iWork.
This is very convenient for me and I am very satisfied but I would just like to know if you can explain why this application is not within the cloud computing system?
I would very much like to use this application. Thank you in advance for the help.
