I agree with you. The netbook-nettop or similar is the base platform for more "abstract" intelligent computing, or heavy task as computer vision. MCU can optimally do the sensor interaction, or base task as could be PWM on motors, servo loop, etc. And today there are cheap microcontrollers that are really "beasts", indeed they could do also some type of computer vision computing. The great advantage of standard architecture pc, as netbooks, is that they can use a bunch of very cheap peripherals: webcam, bluetooth or wifi devices, memories, and so on. Connecting similar peripherals directly to a microcontroller is not so easy, and not so cheap.