Teaching kids some proprietary thing that is only available in a special situation, versus teaching them broadly applicable skills that are entirely relevant, after 40 years of computing history, is very much more valuable - as a parent - than the alternative.
Also a parent, also learned to program on an 8-bit system, taught my kids computing with the Raspberry Pi and they still use them for things way beyond the Minecraft zone... just yesterday the younger of the teens figured out how to use his rPi to catch his older brother entering his room. Sure, he could have done that with the micro:bit too - but that would have been an artificial ceiling for things - as it stands, he's been spending the morning working out how to get his brothers' guilty pics uploaded to the family NAS, which is another extremely valuable skill that this teenager has now developed in a matter of days, which would not have been easy to attain with the micro:bit.
I think the micro:bit, as has been mentioned earlier, is proprietary and limited. There's nothing to learn there that can't also be learned on rPi, and the rPi gives far better future-proof opportunities.
The only 'advantage' is that micro:bit might be easier to teach - but that is just excuse-making for poor educational standards. I'd much rather my kids' teachers have the skills and ability to teach them future-proof computer subjects, such as the raspberryPi (the younger one has now just asked for their own Hetzner account) than limit them to proprietary stuff that isn't available anywhere else in the world ..
It is beyond embarassing that we are graduating students who don't know the difference between a File and a Folder, or why you need to format storage devices, or even what a storage device is .. micro:bit will re-enforce that ignorance in a generation of students - raspberryPi entirely discourages it and prepares the student better for the world, imho...