I have created a dummy basic project in VS2015 Community Update 3, Version 14.0.25424.00. (Using this great tutorial: aspnet-core-web-api-angularjs-2 ).
<WoW, poor Microsoft..
The issue here is that on installing VS2015, I got TypeScript 1.8, But it didn't update the PATH env variable of Windows 10, So I was actually using the 1.0 version.
I had to update it manually with the help of THIS POST .
(be aware of the comment there to use "compileOnSave": true on win10 os).
Now it's WORK (-;