Anyone question why Iran shouldnt have the bomb?
1. They signed NPT and have to fulfil their obligations. If not sanctions have to be imposed and obeyed to give all other signature nations pause for thought, otherwise you might as well tear it up.
2. They are a theocracy lead by those who a publicly uttered belief in the imminent return of the 12th Imam and an intent to remove Israel from the map. It leads to the thought that they will not behave in what other believe is a rational manner.
3. They are one side in a Sunni/Shia, Arab/Persian regional power and arms race. Both Turkey and Saudi Arabia are known to urgently pressing ahead with development/procurement of their own ballistic missiles and ability to produce their own warheads. Others are probably doing the same. Do you really want the whole new Middle East armed with nuclear warheads in the hands of mutually antagonistic theocracies?