I have to admit that part of the fascination I have with MorphOS and Amiga OS is the fact that "elusive" hardware is required (even more in case of the latter). But looking at it objectively MorphOS x86 would:

1. Make itself even more accessible
2. Possibly convince some Amiga OS users to switch, or at least try it
3. Make it easier for open source software to be ported (I stand to be corrected)
4. Allow MOS to run on brand new, relatively cheap components which can be bought from the local PC store

Frankly, I can't wait.