Why? Why should I need/buy one?

RaspberryPI is a relatively good "PC" for cheap, uses little power and is fast enough for most usecases at home.

RaspberryPi zero is a bit slower, but a lot smaller.... and harder to buy.

Neither of them have any good alternatives on the market (yes i know many other similar boards exist, but software support is really shitty for those "alternative" boards, especially after a few years).

Why PI Pico? What killer feature does it have, compared to esp32 (which has wifi), arduino (which as a gajillion libraries and support), or some other microcontroller (bbc micro, STM,...)?

EDIT: not trying to shit on their effort, but genuinely looking for an answer to "why this, and not something else (arduino, esp,...)?"