We would like to use team calendars to track and report on where team members are/were. The description field is too free form. Being able to associate label for team events like (sick, offsite meeting, vacation) would improve the quality of the information.
For event calendars the ability to associate labels would allow a department to have a single calendar (instead of many) and manage different types of events, for example our HR department hold difference types of events (training, lunch-n-learns, meetings). Currently each of these needs to be managed with a different calendar. Add on top of this that our company, and many others, have many departments and you get calendar explosion.