Why? because it was human and funny too - it was like the developer was reaching out to me and giving me a personal experience. It's a nice touch. I came away from the crash feeling weird - not the normal frustration but an acceptance that, ok, we're human and humans make mistakes.
Ergo; because humans make software, software will always have mistakes in it.
Oh, yeah and it did require me to close the tab I was using, but not a reboot of IE.