Some readers have added to the list of these odd sounding words:
Interestingly, trammelled and requited were the only words from this list that spell check accepted without the negative prefix attached.
On a separate note, in the original post I asked for readers' thoughts about a name for this phenomenon. I received these two wonderful responses:
antithesislessness from The Virtual Linguist
a theory of negativity from Freckled Writer
"One way to not be illusioned is to never have been disillusioned."
- Author unknown