But who would guarantee in the event of a conflict that Iran finds itself in, that the computer systems of those SU-35 planes would continuously function without original makers or others sabotaging them? An indigenous Iranian fighter jet, while it is far less stealthy and less potent than the SU-35 today, at least alleviates that worry from Iranian leaders.
During the Gulf War II in 2003, for some reasons that haven't been explained, Iraqi SAMs stopped working in the 3rd week of the invasion. Who caused them to disfunction? I haven't seen any reports; however, sabotages and EW perhaps were clearly the reasons.
Indigenous weapons have advantages that more advanced, foreign-made weapons can't guarantee you in the event of a conflict: reliability.