Issue with setting up sass

I installed ionic2 for a few months, while I was working on my current app. Today I tried to install other ionic project, it looked fine until it came down to setup sass. I couldn’t find ionic.project file for manual installation and also it doesn’t recognise the command “ionic setup sass”. On stackoverflow, someone suggested I should use “ionic serve”, ionic.project would appear after. But in my situation, it didn’t happen.

Cut this short, I reinstalled ionic with the plain old ionic and with the ionic.project file was still missing. After I tried “ionic serve”, it was still missing. Then I tried “ionic setup sass”, now sass is working and ionic.project is here.

Would appreciate if someone can explain why here? Is this expected behaviour?

Sorry being a noob, does this mean ionic2 supports ionic code but not allowing us create more new projects?

also does this mean, sass is part of the ionic2 that we don’t need to set it up?