The reason the Iranian theocracy exists is because the US toppled Iran's democratic government and put the Shah in charge. What makes you believe that regime changing the current government will lead to liberal reforms?
If the US did it before (regime change), couldn't it do it again?
That's not the question, the question is why would the outcome be better.
If at first you don't succeed...
Trump is only effective at toppling the governments of democratic societies who foolishly welcome him in. Seemingly inapplicable to Iran, since as you say the current regime won't walk away.
And the hardest part is ensuring the new regime can stay in place. That would suggest boots on the ground for a while ... and a while could be several decades. I think the question is whether it would be worth the cost and effort. We still have 28K troops in Korea. I think Iran would require more troops.
Topless and miniskirt policy applies on lolita express jet, back home they have to comply to domestic rules.