Wow, you have pretty high standards!

High standards are good.

A running platform is also good.

Raspberry Pi has 2 binary blobs - the boot blob & the GPU blob. Personally, I'd prefer if they weren't needed.

But I think the availability of a cheap, widely deployed and capable computing platform is more important.

Yes, there are other choices that could be made for the hardware. People should be encouraged to explore those other options.

Nevertheless I think the decision to build something on RaspberryPi is a good one.