Categories are extremely helpful for organizing content on Portal (and AGOL). The problem is that since there is no way to make them required, more often than not they are left empty so the benefit of using categories to organize Portal content is not practical without constant/daily review and management by portal administrators.
While training users and requesting that each new item should include a relevant category value, if that's not enforceable then it's not going to work - especially in a large organizations with many users creating content.
The best solution would be to include a setting in Portal that would require a value in Categories if this setting was turned on. That way Portal Administrators could decide whether or not they wanted to make assigning Categories required or not.
