Problem: is that any Mass Update changes the "Modified By" information. "Modified By" information is to see when a regular user changes something. Now, if a user goes to a Lead 1 year old and it is there "Modified By" an admin and yesterday (because there was a new workflow and did run a mass update), it looses any purpose.
Solution: Add a checkbox when picking the field for Mass updates named "Skip Modified By". Make it only for Admins if you want. This way any Mass Update to activate Blueprints or Workflows will let "Modified By" information as it has to be, changed only by regular User.