Freedom to modify any part of your environment live in an Image is wonderful when your changes work perfectly, and horrific if you make any low-level mistakes; you can easily destroy the tools necessary to back out changes to your tools. It gets even worse in a world where you might run code from someone else with malicious intent!
I think it's generally better to aim for what the old C2 wiki called "Alternate-Hard-And-Soft-Layers": substrates that are less malleable with dynamic layers floating on top. We can do much better in terms of malleability than mainstream operating systems without descending into the complete insecurity and fragility of a classical Lisp Machine or Smalltalk environment.
I think it's generally better to aim for what the old C2 wiki called "Alternate-Hard-And-Soft-Layers": substrates that are less malleable with dynamic layers floating on top. We can do much better in terms of malleability than mainstream operating systems without descending into the complete insecurity and fragility of a classical Lisp Machine or Smalltalk environment.