YouTube has removed the category browsing several months ago. Yet YouTube users have expressed many comments / concerns. Finally YouTube editor added back the category browsing and users are now very happy about it. Browse here for the YouTube Editorial Team blog which outline such changes in the last few months.

It is not surprised to understand why YouTube is so popular.

• Category Browsing is important / critical to users (even though Search is so popular nowadays).
  

• Open environment to take users comments (login members) to improve the website with an open blog / forum for users comments + youtube proactive feedback, making the website more user centric and sticky.