Failed to use UI Framework module

Following steps closely on using UI Framework in your module , I configured things as required. Now I started following steps on UI Framework Step By Step Tutorial . I created a simple basic module but with just on demo page but when I try accessing it at https://localhost:8080/openmrs/uitestframework/ I get the following error

Let someone help me out . cc @dkayiwa @darius @raff

Can you upload your module on github and i take a look?

Its here

The convention is that if you need to access, then you need a demo.gsp. I see that yours is demo.gsg

You will also need a DemoPageController.

That being said, going forward, we do not encourage using that ui framework for new development. Our recommended approach for doing user interfaces is found in the resources below:

But why is the UI Framework discouraged for new dev. Is it considered obsolete?