[TickleSteve]

The setup process involves some audio processing which requires slightly more than trivial signal processing and also some RAM usage... Also handling the network stack requires some RAM. The combination of those two requirements and the low cost of the STM32s of that level of capability mean it was probably a sensible choice.

[zwieback]

I'm surprised they went with F205, though. There are 32Lxxx chips with similar capabilities and lower power.

The whole thing looks like a quick turn of a reference design and the real low-cost design will follow later on.

[TickleSteve]

I would agree. It looks like a quick&safe design.... If it takes off, a cost-optimised version will appear.