I think it's a matter of privacy and security... no different than changing the User-Agent string for your web browser, or the login prompt for telnet if you run the service. Why make it easy for someone to figure out what exploits you might be susceptible to.
I can appreciate Khaled wanting to receive credit for his work though... perhaps the ability to change the default version reply could be made available on registered clients?
Then again, the version reply is also a tool IRC admins sometimes need to use when dealing with network issues.
