The main criticism of the Iran deal under Obama was suspicion that Iran never stopped enriching. I personally think that's correct, and they hid some level of research and development in preparation of enrichment, if not enrichment itself under the JCPOA. Trump currently cant get a deal done, but maybe the memorandum will go through.
I still have a hard time calling just possession of their HEU as a real win. They're going to make enough missiles after the war that they'll be a permeant threat akin to North Korea. The Kims have never really been a nuclear threat, that's new and we still have doubts if they can deliver a payload despite some of their wonky tests. They're a risk because of conventional missiles aimed at Seoul and Tokyo, which they can 100% deliver.
So even if we get Uranium out of the way the neocons are nowhere near done with Iran. Even if they never enrich another gram.
The problem with jcpoa was not that they were enriching past it’s bounds(until 2021 they were not), but that they were explicitly allowed to continue to improve their enrichment capabilities. This allowed them to enrich a very large quantity of uranium to near weapons grade in a relatively short amount of time once they made the decision to do so.
This(in conjunction with confiscation/destruction of their HEU) is what needs to be addressed in the new deal, as I said.
Nuclear weapons can not be intercepted as easily as conventional missiles can be, as nuclear payloads are MOST effective when triggered high above their target. So, yes, acquiring nuclear weapons makes a country much more dangerous than even a very large stock of conventional arms.