Trying to find a clear line of "good vs evil guys" is bound to led you down a bad path. Is how Iran treat people very shitty and outright evil? Yes. Does that mean other countries should feel OK with invading them to "liberate" them? Probably no and feels like a very dangerous line of thinking that could be used to invade basically any country, including the US itself.

I don't think many people are arguing that Iran is some beacon of democracy and treating their people right, but regardless of that, we tend to favor sovereignty of nations for a good reason, yet it seems like some countries still struggle with accepting this.