I am not real familier with the concept of tagging, but from what I have been finding out, its the future. The traditional subject heading approach is not adaptable enough in the fast changing world of the new information. Thus you have one subject heading for an item. In Tagging you can use an unlimited number of tags to identify one item. This helps in locating items when searching.
In Tagging there are problems due to lack of control. Anyone can tag with any term and this may be open to someone going to the extreme. The article referred to tag spam, where people apply an excessive number of tags in order to attract visitors.
Tagging can be used as a compliment to the traditional subject headings. It can enhance the ability of a person to find the information they are looking for. Thus it should be encouraged, as long as it does not get out of controll.
I look forward to investigating this subject further.