Current preference for full name adds unnecessary obstacles to character tagging. Would be better to prefer name_(<character_owner>) format, as it provides additional information that makes it easier.
The most common case: artist omits character names from original post description, and the only information you can go off of is character owner. If a character is tagged with full_name on e621, usually you have to rummage through their gallery to hopefully find it mentioned somewhere. With name_(<character_owner>), you can search on e621 for *<character_owner>*, or even put <character_owner>) into tag box to have it pop up as a suggestion.
It's extremely rare for artists to provide full character names. At best it's the first name and character owner. If a character is tagged with full_name on e621, and the name is not unique, you either still have to rummage through their gallery, or search for firstname_* and hope to find the character there. With name_(<character_owner>), just type it in that format.