I would like to hear Mr. Tanenbaum's answer to the less provocative form of the sentiment: "What design decisions were made with MINIX3 that other RTOS with microkernels didn't consider?"
And Minix isn't a micro kernel in the same way that QnX is.
If something didn't work it was either hardware or our own code, the way it should be. It's not magic but it is very good at what it does. And it is a way of building things that just works, message passing is a very powerful technique for making reliable distributed systems.
To me this sounds a bit funny - isn't the whole point of microkernel architecture that you achieve the reliability by simplifying the kernel - it's a less complex piece of technology, so it can be more reliable, and the complexity is offloaded into user space processes.
Yes, it does not do what it should not do, because it does less.
It's just that with the microkernel more of the code will be in stand-alone programs. Every driver, file system, network layer and so on will be a program all by itself.