I forget exactly, but I believe that the original reasons the macrokernel was chosen over the microkernel are largely moot now. The microkernel was always more secure, if my memory serves. That is more important now than it ever was. I need to check but aren't we still behind on full 64 bit adoption? I would be think that we be better achieved through a newer kernel/OS. Lastly, AIs are still relatively new and not as locked down and/or expensive as they may become for specific purposes. Couldn't they help reverse engineer drivers? Which I would think would be one of the largest obstacles. I've read about Redox in the past, but it seemed to be a one man project that was largely abandoned for years and after 10 years it's still not out of beta, if I'm not mistaken.
I'm a middle aged +, amateur user/enthusiast. So, I'm really asking. Lastly, I wonder if the Linux kernel is like the Weasley house in Harry Potter i.e. kind of a monster with parts on top of parts , with the whole being more unruly and although functional is a bit of an unruly mess at this point that doesn't resemble anything like a good overall design like a good "new" house could be. Again, just asking. Most of this is well beyond my understanding.