So maybe my new conclusion is that Smalltalk is uncompromising in its vision, but the world is not ready for that vision.
Agree with that. The fact is that Smalltalk, despite it exist since...30 years? did not get wide audience in real concrete applications, I mean the kind you pay money for. My feeling is that it is in advence on its time or century. What we can see is that widly spreaded languages and platforms (java, .net, Windows, etc...) are converging toward concepts that were built in Smalltalk since its beginning. Hence, I think that even if it is hard for us to forgot our way of thinking from data/process world, it is rewarding to embrace the "Smalltalk way of life". You get a new vision of what can do computers and how to use them.
Of course, at the end of the day, you will go back to Java/C# for your industrial applications, but with a new vision of how to architecture your system. Look at Kent Beck, and such guys: they came from Smalltalk to really deeply improve our way of working in Java/C#.
To come back to the reasons of Smalltalk failure, I agree with your social interpretation of programming, from another blog: Because computing is functional, because it is social, I think it must develop in an incremental and continuous fashion. Revolutionary ideas have to be parseled out in small packages, or be optional, and Smalltalk doesn't seem to offer that.
However I expect that classics languages are slowly but surely moving toward Smalltalk.