It would also be extremely easy, just a few lines added.
The problem really isn’t the difficulty of coding it - it’s that the board administrators are very reluctant to make any changes to the board software, regardless of their difficulty (or lack thereof). Every few weeks someone makes a good suggestion in this forum for an improvement, but it never gets implemented, for that reason.
Apparently, they’re worried about the difficulty of maintaining changes through software upgrades, and worried about potentially breaking something (or making it difficult for vBulletin to provide support if something goes wrong).