I am absolutely right about that. Which of the English renditions it equates to varies depending on the situation and the intonation, and it doesn't always have a negative connotation, so I would caution any Japanese learners to not take a simplistic approach to いいから and just assume they can substitute any of them anywhere willy-nilly. You are entirely correct about "mou ii kara". It also varies wildly depending on the situation and intonation, with anything from mild annoyance to resignation to indignant outrage being encompassed by it.