The Ottoman Empire was [not an Arabian empire][1], but a Turkish one. So they had no reason to uproot their capital from Turkish lands and move it to an Arabian region.

In addition, <s>Constantinople</s> Istanbul was way better than Damascus, Cairo, and Baghdad at everything. It had a strategic position on the Bosphorus Strait, it was the crown jewel of the Eastern Roman Empire in terms of culture and wealth, and it was even close to the previous Ottoman capital, Edirne. It was well-defended with two sets of famous walls. 


  [1]: https://history.stackexchange.com/questions/10318/why-was-the-ottoman-empire-not-seen-as-an-arabic-empire