Kay and Ingalls et al. had a very specific vision for personal computing as liberating, and the keys to that vision were full access, full comprehensibility and making no distinction between users and programmers. The market has clearly shown that people would rather not have full access, don't care about comprehending the system and desperately want a firmly regimented distinction between users and programmers.
For me personally, the thought of giving up entirely on this vision is repugnant and it's important, even if such systems aren't going to make a grand reappearance anytime soon, to at least make sure that people who care about computing know that they once were. I see that reminding as Kay's primary role. I'm not switching to Pharo for my day-to-day work (in my defense I did try) but I find the philosophy appealing and don't see a compelling philosophical disproof. So it seems to me it could re-emerge someday, and a world built on these ideas will have different tradeoffs, and may be preferable.
Don't mistake the fact that normal users aren't interested in current tool chains and coding means that they aren't interested in being able to solve problems creatively. Kay mentions Hypercard in this interview, which had a long history of drawing normal people into designing solutions to their problems from scratch.
Back in the mid/late 80s I used to do work for a public library and helped set up several public Macintosh computers that had, in addition to word processing and spreadsheet software, Hypercard installed. I was amazed how people "got it" so quickly. From kids, natch, to street people to soccer moms. And by "got it" I don't mean running the built in stacks, but in creating their own.
Before long I was helping people make some really interesting projects. Some of them were beautiful monsters, but others were very well thought out. And all of them solved specific problems, many of which would not have had enough general appeal to be marketable or even transferable to anyone else.
And there's real value in having that ability. But these days most people simply can't get past the gatekeeper of beginning complexity. To be sure, in Hypercard you quickly ran up against a wall of limited extensibility in terms of its objects. I can easily imagine better.
But Kay is right, The web and most modern OPP aren't it. And modern tools for software development are a nightmare.
The market has no incentive to create a system that hands users a microscope that shows what is happening at the cellular level, that can, as a natural science not programming, demonstrate what is happening. To say the market has demonstrated that people don't care about comprehending is false: the market has not found a marketable way to sell explodable systems, and CS has not created runtimes that can illustrate their functionality, can be introspected into, in a high level or compelling systems view.
_The big problem with our culture is that it's being dominated, because the electronic media we have is so much better suited for transmitting pop-culture content than it is for high-culture content. I consider jazz to be a developed part of high culture. Anything that's been worked on and developed and you [can] go to the next couple levels._
I'm not sure that our media is necessarily better suited towards transmission: I suspect we just lack mediums that make looking at what is happening evident and interesting (even with X years of programming experience, watching another persons webapp run is rarely fun or an obvious exercise). This is a failure of our runtimes and the weak structures we use to build code.
For me personally, the thought of giving up entirely on this vision is repugnant and it's important, even if such systems aren't going to make a grand reappearance anytime soon, to at least make sure that people who care about computing know that they once were. I see that reminding as Kay's primary role. I'm not switching to Pharo for my day-to-day work (in my defense I did try) but I find the philosophy appealing and don't see a compelling philosophical disproof. So it seems to me it could re-emerge someday, and a world built on these ideas will have different tradeoffs, and may be preferable.