I was recently attempting to add a new managed metadata type site column to an existing SharePoint 2010 site collection but when I tried to select a term set I saw the following error:
The required feature is not enabled for this column type
This had me a little confused. I checked all of the features against another SharePoint 2010 server that was working as expected and everything appeared to be the same.
A search on Google revealed that there are actually some features that are not listed in the site features or site collection features that can (somehow) become disabled and will then need to be manually activated using STSADM.
STSADM -o activatefeature -id 73EF14B1-13A9-416B-A9B5-ECECA2B0604C -url http://sitecollection -force