Most likely because it is hard to get it and hard to use it. Remember you have to have internet connection and a mobile phone at least to buy it and use it. Not everyone has that, and that is holding it back. In my opinion at least.
Most of the people living in cities such as Baghdad and Basra are having broadband internet connection, although the same can't be said about the rural areas, such as the ISIS-infected villages of Al-Anbar.
Is this true in Iraq? Broadband?
Almost everywhere in Iran, even Tehran, was 56k connection in internet cafes. Only in companies did they have broadband