To add, knowledge of Turkish will also make it easier to converse in Azerbaijan, Uzbekistan, Turkmenistan and a bunch of other countries in the region.
To add to that, I learnt to basic-speak the now extinct language of Chagatai, because I know Turkish.
Turkish is also mutually intelligible with Uzbek and Kazakh - it's basically like English and Dutch.
Edit:- Learning Chagatai practically let's you speak Kazakh and Uzbek partway. Tried it in both countries, might work in other places like Kyrgyzstan and Turkmenistan too. :)
More than half of the Iranian population belong to an ethnic minority, and the biggest by far is the Turkish speaking one, the Azeri - it's something like 1/3 of the population as far as I remember. I don't know if non-Azeri learn Turkish from TV, but for a lot of Iranians it's simply their first language.
Turkish is also mutually intelligible with Uzbek and Kazakh - it's basically like English and Dutch.
Edit:- Learning Chagatai practically let's you speak Kazakh and Uzbek partway. Tried it in both countries, might work in other places like Kyrgyzstan and Turkmenistan too. :)