Lightroom :: Keyword Tags - Why Can't Add Keyword Tags To Multiple Photos

I have used multiple versions of Lightroom (2, 3, 4, and now 5).  Why can't I add keyword tags to multiple photos?  I know that it can be done while importing, but I usually import a whole day's worth of pictures at one time and they don't require all the same keyword tags. The ones that are common I do add during import.  I used to be able to highlight the photos I wanted to add tags to, go to the metadata and find find the list of keywords applied to those photos.  Tags that were not common to all photos has an * beside them.  If I wished to have one of these tags for all the selected photos I just removed the *, otherwise I added the new tag to the list.