why do I have to use the xfinity app to enable DMZ and port forwarding

When will we be able to do  advanced functions in the XER10 admin page.  I don't like clicking on the DMZ section only to be told to do it though the app.  Do I have the app on my phone...yes, I do.  Do I want to track down my phone when I can just as easily login tot he web admin portal and make my changes there...no, I don't. I used to deal with the Motorola SBG900 and it was better setup than the XER10 is nor and that was 17 years ago.  I would just like to be able to have those abilities put back into place.  Thank you.