I may be biased but to be honest the way I see it is that BRICS without Iran didn't mean much. Specially when you consider the historical role Iran (or Persia) played in the global economic scene for centuries connecting East and West by being at the heart of Silk Road, and it still is at the heart of the new Silk Road under the new name One Road One Belt.
This is an important point. Iran's location is its blessing as well as its curse, and this has been proven by the facts of history. Since the Middle Ages, travelers used to call Persia "the key to the East" until the construction of the Suez Canal, which reduced Iran's role in world trade.
It is important to address the reasons that delayed the formal inclusion of Iran in the BRICS since its inception, the most important of which is the international pressures on Iran since the fall of Reza Pahlavi (supported by America and the West) through the Islamic revolution in 1979, followed by a regional war against Iraq that lasted for 8 years (Saddam Hussein was supported by America at the time). Then, after the fall of the Soviet Union, Iran did not come out of the American Western considerations represented by the occupation of Afghanistan and Iraq and direct intervention in the Caspian Sea region through the establishment of a system of Eurasian corridors between Turkey, Azerbaijan, Uzbekistan, Kazakhstan and Georgia in order to achieve the geopolitical isolation of Iran because of the Russian-Iranian rapprochement that harms With American interests, according to which Iran will have two options, either to submit or to confront a hostile environment on its northern borders. Without forgetting to fuel the sectarian conflict with its Arab neighbors and to put more pressure on the background of the nuclear issue.
I find that these pressures are enormous, and it is really exciting that Iran has succeeded in steadfastness and the establishment of international alliances with such solidity. The BRICS countries were not able to declare a direct confrontation against America by officially accepting Iran's accession, and the cooperation remained formal. Today, the BRICS group feels stronger and that the announcement of Iran's inclusion in it will not meet any objection.