The president isn't unimportant though. A sad fact about Iranian politics is that the two times they elected a reformist president - Khatami in 1997 and Rouhani in 2013 - it was followed by the election of a Republican president in the US who spat in the face of attempted conciliation.
Bush grouping Shia Iran into his 'axis of evil' and trying to link them with Sunni Al-Qaeda, and then Trump's binning of Obama's carefully negotiated nuclear agreement, has done an enormous amount to undermine the reformists as ineffective and to strengthen the hardliners around Khamanei. It doesn't get talked about enough: there's a weird sort of codependency going on between Khamanei's crew and the US Republicans.