This works for smaller amounts of data, but hierarchies are still needed to sort very large amounts of data that have to be accessed at any time. Yes indexing/searching/filtering is an option but when you have 1GB of pure text, searching "the company" is gonna get you several hundred hits. Google excels at this because they've created ways to dynamically optimize their results via user input. However no one is gonna do that for your private docs.

Personally krunner like gnome-do is useful but not for searching my files, because it gives no context. Someone needs to create a good kde app/plugin for context able searching through strigi.