Faster prototyping, I can ssh into a RasPi wirelessly and control the gpio via my terminal like a REPL, for the ESP I need to keep flashing newer firmware and control it via USB to serial. Feels a bit clunkier although not a huge difference.

If I were making and selling some IoT hardware or if I wanted to re-use the RasPi for something else in my house, it would definitely make sense to move to an ESP/Arduino