So... let's asume I have VB v2.x installed and I have no time to upgrade.
A critical security leak is posted and every1 is urged to upgrqade. I have no time to upgrade but ANYONE (not only a hacker) can use the exploit to mess my VBulletin in 5 seconds...
Repeat: WHY do my audience need to know which VB version I run? They don't need that information AT ALL, they won't develop anything for me on my VB forums... so WHY?
And on a secured system, there are ways to hide Apache version for example... at least mine is hidden.
You can edit the version number within the setting table to something useless like 4.0.0. This will confuse the new version notification system in the admin CP, however.
I know where you're coming from; I removed the vB version number on my site from all publicly visible templates because there is no need for anybody to know it.