I essentially don't have a strong electrical engineering background. My knowledge consists in playing around with Arduino based microcontrollers or Raspberry Pis or equivalent SoCs.
What is the reason why a company would choose to design self made electronics with programmable microcontrollers instead of having a central SoC which runs an ordinary operating system, e.g. Linux, to handle all sensor inputs and processing. The target processing rate of sensor data (say 180 kB per time step) is 100-1000 Hz.
My idea behind this is the following:
A Raspberry Pi costs ~30$ and can handle all kinds of software, while a programmable microcontroller is essentially bound to compiled code in some self-written semi-compatible C/C++ language. Thus the development and maintenance cost for a SoC is way better. The processing frequency (max 1 kHz) makes me doubt that sophisticated hardware is needed here. Let's assume the processing steps are not too complicated. Assume that the CPU cost is not the main factor of the product cost. Size is neither a problem (A Raspberry Pi would easily fit). What are the bottlenecks of running a SoC in such a setup and thus prefer some self made boards with programmable microcontrollers (or even FPGAs)?
Assume the final product will be sold at 10k-100k$.