The deal is deeply flawed. It will likely create serious strategic costs for any future confrontation with Iran. But given the options, it was probably the least bad choice.
A naval blockade was not going to force Iran to surrender. Returning to war would have caused massive economic damage, with no guarantee of Iranian capitulation. In the end, Trump was forced to accept Iran’s terms because the alternatives were even worse.
This is a very bad deal but it may have been the best available option after a campaign that became a strategic fiasco. It was built on a profound misunderstanding of the Iranian system, and it has likely produced a more extreme and more determined Iran.
In American terms: you break it, you own it. Israel and the United States may not have succeeded in toppling the Iranian regime, but they did shatter the fragile stability of the Gulf, and, to a significant extent, the stability of the global economy, without achieving regime change in Iran.
At that point, it became America’s responsibility to restore at least a measure of stability to the global economic system, even at the high price of accepting the survival of the Iranian regime, strengthening it economically, and allowing it to preserve much of its conventional capabilities.
It is an extremely costly price to pay. But when the alternatives are bad there was no other way. when you break the system, you own the consequences.