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.