> we shouldn't have to have a JCPOA in the first place, they can just not pursue nuclear weapons like almost every other country on the planet.
Other countries do pursue and have nuclear weapons. Iran has not yet created a full nuclear weapons program - or hadn't before the current war.
Iran, being under constant threat from the US and Israel, with open calls to attack Iran for decades; seeing two neighbors recently deposed by the US (Iraq and Afghanistan); and having had their own government deposed and replaced by a US-friendly one (Mosaddegh in 1953); under constant threat from neighbors and the region (Iraq invaded in the 1980s, Saudi Arabia and other Sunni states are open enemies, Israel of course); may believe that they need nuclear weapons to survive.
Is there another country in a similar position, with the resources to develop nuclear weapons, that doesn't have them? North Korea and Israel both made that choice in similar circumstances.
The US 'nuclear umbrella' covers its allies around the world, a very effective non-proliferation tool. Otherwise, I imagine South Korea, Japan, many NATO countries would build them - there is already discussion of it in the former two countries.