That is funny! It does seem to lose its punch that way! Thanks James you made me laugh at that one. Point well taken!!It's just my understanding of the register of the phrases. I can't imagine someone in a heated argument in casual conversation saying:
"God damn it, Louise! You've been a pain in my ass from day one. It would have been to my advantage never to have moved in with you!" rather than "I'da been better off never moving in with you!"
That looks to me like a mix of informal and formal registers. I may be wrong.