Israel and the U.S. possess complimentary capabilities, which is why  Trump said “it might actually help”:

• The U.S. has superlative technical intelligence and unique strike capability against hardened targets.
• Israel has unparalleled HUMINT (human intelligence) bolstered by the Jewish Diaspora and widespread dissonance in Iran.
• Israel’s strike capability against soft targets is similar to U.S. in quality, though not in quantity or reach. It is bolstered by on-the-ground damage assessment.
• This results in a well defined target dichotomy. Israel’s target is human capital, intellectual property and research facilities. The U.S. target would be industrial base.

The timing was forced by the tendency of HUMINT to go stale. Top generals are easily replaced, scientists less so. Depending upon the depth of intelligence, the strike may impede Iran’s program for a year or two.  However, it is relatively easy to cache this kind of property, both intellectual and technical, in multiple locations, not all of which may be known to Israel.

It is doubtful that the underground centrifuge halls of Natanz can be   penetrated by Israel, though above ground support structures are vulnerable. Entrance portals may be vulnerable to specialty weapons.

The regional trajectory  is unlikely to deflect by much. The inability to  extirpate Hamas should  give pause for a much larger target. Quoting from Iran’s Options for Retaliation,

The leaders and  senior politicians of Israel have all lived through  the unsuccessful attempt to influence Lebanon’s trajectory, to deny terror a sanctuary in Lebanon by skilled military intervention. Despite calls to “finish off Hezbollah”, their inner thoughts must span a range, from doubt of the achievable to realistic buying of time, time of relative security. When the enemy has 200,000 missiles, you have to do something. Perhaps time is all you can buy in the Eternal City._*

Quoting from Iran history II: two societies,

It is the living embodiment of a Plato’s Republic, incongruously set against a secular majority that pretty much does what they please — in private. The dichotomy is so severe as to seem institutionalized hypocrisy.

This culture of centuries resulted from  the melding of Abbasid and Persian cultures. It has produced Iranian negotiators rich in verbal expression and nuanced meaning, delaying  the  onset of “Haven’t we been here before?”,  entrapping Trump’s negotiators in an endless circle of words.

The above should not be construed as an opinion on military strikes. History is  a mighty river that just carries us along. Iran might buy North Korean nukes, which are much more advanced than what they are trying to build.