The differences between Khatami and the current crop are nuances. There is no moderation within the islamic regime.
Only foxes who prefer to smile while building WMDs and lunatics who prefer to rant while building WMDs.
They are far more than nuances. Khatami was pretty conservative and definitely not ideal. But he was pushing for better relations with the West, all-inclusive representation, rule of law (instead of at the whims of the mullahs) and for restoration of the rights of women. He got elected on the youth and women vote, people who were, and are now, pushing to reform the restrictive, hardline government.
Remember that the government consists of two parts: the popularly elected structure and the Guardian Council appointed by the Ayatollah. The Council can overrule anything, and did so for all of Khatami's attempted reforms.
He upset the Muslim hardliners so much that they rigged the 2004 election get rid of the reformers, leading to the installation of Ahmanutjub.