>
> Is there a rationale why `self` in instance view does not raise an error or is nil?

That is because you can write: self new and work with an instance.

> And, more importantly, could there be a way to set it to a specific value (= can we browse a class with self bound to an specific instance).
> This would resemble programming in the debugger, but provide the overview that a class browser provides.

You can do that to some extent in the Meta tab of the inspector.