Two other reasons may be aesthetics, and the environment - Beijing gets sandstorms but it doesn't get typhoons. Per CLP (just across the border in Hong Kong):
> More than 30% of CLP’s transmission network consists of overhead lines. There are more than 700 400kV transmission towers that form the backbone of its supply system. Overhead lines are exposed and susceptible to the influence of weather and the external environment. If a pylon is destroyed by strong winds or collapses because of a landslip, it will take several months to be back in order.
> More than 30% of CLP’s transmission network consists of overhead lines. There are more than 700 400kV transmission towers that form the backbone of its supply system. Overhead lines are exposed and susceptible to the influence of weather and the external environment. If a pylon is destroyed by strong winds or collapses because of a landslip, it will take several months to be back in order.
https://www.clp.com.hk/en/about-clp-site/corporate-informati...