>AROS is way past OS3.9 levels of functionality
No, it isn't. In fact according to their own page
http://www.aros.org/introduction/status/everything.php the OS3.1 implementation is only 82% complete, let alone OS3.5/3.9 support.
>>Amiga development will be effectively stuck in 1994.
>That is perhaps the goal of most Amiga developers
Unfortunately that seems to be the case.
>To equal the functionality of OS3.9 was never a goal for AROS
That is exactly the problem. How can it be an Amiga Replacement Operating System if it doesn't replace AmigaOS?