I had similar experiences as Rad Static; I do not remember what version of vanilla FO2 I was using at the time, but I distinctly remember having multiple instances where after 4 hakunin dreams and not having entered Vault 13 that the game would end returning me to the main screen.
Perhaps that was a bug in one of the versions of the game, but I took that as an intended part of the game, and will be doing the test again in the near future to see if it is still a part of the game.
Because if it is NOT I will be VERY disappointed. I think that having consequences for your actions is INTEGRAL to an RPG, and Dicking Around Playing Pattycake With Hookers and Mr. HandyBots While Your Village Is Starving To Death... is something I am strongly convinced should have consequences.
Now I am not sure about it Ending the game, but I am entirely convinced that you should not be able to get a "Good Ending" if you let your village starve to death.
GWT