Perfectly reasonable question, it would indeed be great. Yes, there's a but coming...
...Large parts of the Amiga system (esp the OS) are based on outside companies IP so there would be a minefield of sub-licensing to deal with.
...The history of the Amiga over the last 20 years is such a convoluted mess that I suspect finding who actually owns the genuinely Amiga bits could take years to sort out (much expense) before it could be bought & open-sourced.
...I believe large parts of the OS source & chipset schematics have gone 'missing' over the years which complicates matters further.
Sorry to sound like to voice of doom - it's a good idea, but I can't see it happening. I think we're stuck with our increasingly aged boxes + emulation (very good) + AROS, etc if that's your cup of cha...