It was a big f.u. from the point of view of the Iranians. Taking with one hand what had just been given with the other.
I was working for a big manufacturer of industrial equipment at the time, who were expecting large developments and orders from oil projects in Iran, they even had advance teams being assembled in Kuwait and Oman, getting ready to start travelling to Iran. The sudden change to visa rules caused huge upheaval, with personnel that had to work in the US as well suddenly having to be withdrawn from the teams, and eventually the whole set up was canned, once it was clear that the US didn't really mean what they had signed about sanction relief. I am sure many other companies went through the same process.
Another victim was the Iranian tourism industry. The US ESTA trick meant that after the agreement travelling to Iran was actually more problematic for Europeans who might need to travel to the US too.
Bad faith in negotiations is standard procedure with the US. It didn’t start with Trump, and it won't finish with Trump. Trump just says the quiet part out loud.