While a seemingly good comparison its a bit relative...Iran's first satelite when compared to the other "Firsts" is third smallest which means it didnt require a larger SLV. For example, Israel and China's first satelite were much larger (over 200kg) and were much more sophisticated and long lasting satellites which in my book makes them a greater technological achievement than launching a very simple satellite. Not only that while America's first SLV has twice as many stages, the Explorer I (half the size of Omid) is still in orbit! So less stages isnt always best depending on what you are trying to achieve...As such for most things, achievement is relative.
I don't want to get into the details of the satellites as it was not my point (The advancement of a satellite is not related to advancement of a launch vehicle). Its weight is relevant not its advancement (if not unusually large!). Other than that, the Omid satellite was launched to a lower orbit than Explorer I, which is the reason for its fast decay. The Omid orbit was as they had released it before launch, that is relatively similar to ISS's orbit (it is at much lower orbit that Explorer I). Hence, the goal was achieved which is important. They could have done it with 3 or 4 stages but they did it with 2 stages, which shows they skipped some steps!
In general, getting to a certain orbit with lower number of stages is more difficult (Tsiolkovsky rocket equation). As you should know, at the time of Omid's launch everybody was assuming that Iran used a three-stage LV because they did not expect Iran to be able to do that with lower number of stages.
Personally, among all first LVs I like R-7 the most, here, I don't want to compare LVs togather to see which one is better. My point was that they may
jump some steps as they did in the LV case.