Besides giving MiniMig and the like a compatible OS to run out of the box, it would also allow AROS x86 to be backward compatible with original Amiga software. With the UAE integration that has happenened, 68k software running on AROS x86 looks pretty good. The achillies heal of this it the fact that to legally run this you have to buy a commercial product. So, AROS x86 is backward compatible, but the backward compatibility is not open source like the rest of the OS.
If it helps you appreciate it, just think of it as Amiga68k.hidd.