Good description in that, thanks. My interpretation is:

Electromagnetic motors can be made more powerful by increasing current requiring more copper. Easy. The main downside is that the efficiency boundary appears to have been reached. A step increase was made by using the newly available magnetic materials, mainly mined in Africa, as used in wind turbines, all made in China.

Electrostatic motors lack power and versatility as there is no effective and cheap dielectric material available, perhaps this limitation is now overcome with advances in materials science.
Another problem is in controlling and placing the electric field. Advances in solid state power semiconductors may be solving that issue.