No, they actually aren't. Most of the complexity in a consumer vehicle is not in the powertrain, though a significant portion is. As far as the powertrain is concerned, the main savings in complexity is dropping the transmission and differential (or transaxle, depending on the design). Energy storage and loading is far more complicated on an EV than an ICEV, and the motor control system that replaces the transmission/transaxle is far more complicated than the engine control software that runs an ICE. Also, electronic fuel injection is not really that complicated.