Visual Studio 2013 supports the Phone projects out of the box with no need to install the phone specific visual studio build.
HTML5 games on Windows 8/8.1 DO NOT support the game pad. Internet explorer does not support the GamePad API and it is the underlying engine for rendering HTML5 games on Windows 8/8.1. They are pushing Touchscreen as opposed to controller. I have spoken to some of the Evangelists for HTML5 and that is the focus on windows 8 for games is touch integration. Unless someone has some clever plugin to get the GamePad API to work in IE, then you are pretty much hosed there.
On another bright note though, Windows Phone 8.1 will finally support WebGL so at least WP8 games will now be more realistic.
And to the points of "Why do I need to use windows 8 to develop for windows 8?"... that is a very lazy approach. If you want to develop for a platform you need to be able to test and debug and test some more on that platform.
Telling Microsoft not to charge for their OS is like telling Chevron not to Charge you for Gas, or Baskin Robbins not to charge you for Ice Cream...