In workspace you can tag even props, eVars and events etc. Right-click the dimension in Workspace navigation/search and you have the option to add tags. I tested this, and other users can also see my tags. So I could make e.g. 10 kpi metrics with #kpi tag and this way product owners will easily find all the metrics that matter. Love it!!!
Of course it would be better if admins could add/modify/delete all tags directly from admin section where e.g. eVar variables are listed nicely on the same page. Now it is bit time-consuming if I want to tag 30 different eVars for example directly in Workspace -> have to do 30 searches before tagging, well maybe not 30, but a lot compared to managing these in admin section. and of course as admin I need to sometimes modify what other users have tagged.
And maybe even better would be to have 1 "tags" page where we could see all tags, starting from segments and calculated metrics etc, and it would be then even easier to manage tags.