The problem is the Internet. Or, more precisely, other people.
Those systems of old didn't separate between "an user" and "a developer" because they assumed all users are trusted (and responsible people). With the Internet, this assumption immediately becomes false - between people attacking the network and social engineering, it's dangerous to let people have that much control over their environment.
Which is something that pisses me off, because I'd love to work on a modern-day version of a Lisp machine, but I understand this can't ever become mainstream (and myself I'd be worried using it to do my banking).
Or, as I sometimes phrase it, Star Trek-level tech requires Star Trek-level society.
Networked computing is just a mirror. We seem surprised when some of the things we see it aren’t very nice, but perhaps we shouldn’t be.
More than that: ads. They really did destroy the internet.
Sometimes I think a lot of people do use LISP machines. It's just called emacs.
I joked on here once that I think the end game for GNU/HURD was ultimately to become a LISP machine via emacs, and if you look at some dev setups, that's not too far from what macOS and Linux are for them today: a place to run emacs and a web browser.
"GNU will be able to run Unix programs, but will not be identical to Unix. We will make all improvements that are convenient, based on our experience with other operating systems. In particular, we plan to have longer filenames, file version numbers, a crashproof file system, filename completion perhaps, terminal-independent display support, and eventually a Lisp-based window system through which several Lisp programs and ordinary Unix programs can share a screen. Both C and Lisp will be available as system programming languages. We will have network software based on MIT's chaosnet protocol, far superior to UUCP. We may also have something compatible with UUCP."
One interesting thing about the original plan is that Unix was essentially text only back then. Part of the idea of making it more Lisp Machine-like was to have a GUI, so when Unix got that (with X11 eventually winning) this part of the plan became less urgent.
I suppose an Emacs OS would be sort of a GUI but not quite?
But that was just one application among dozens others. Applications usually were not based on Zmacs, with only a few exceptions: on a Symbolics: Zmail and the Concordia documentation editor application frame. Other tools were not Zmacs based: Listener/REPL, the debugger, the directory editor, the font editor, the PEEK tool to view system details, the document examiner, the tape tool, ...
M-x eval-region, M-x eval-last-sexp and M-x eval-buffer are your friends. Emacs is, as suits a Lisp system, strongly runtime-modifiable. It even has its own REPL - M-x ielm.
Emacs is a tiny portion of what a Lisp Machine was capable of.
So the REPL could display any kind of data structure, and later calls could influence already displayed data.
https://www.youtube.com/watch?v=o4-YnLpLgtk&t=687s
https://www.youtube.com/watch?v=6uPwQuxjgQo
https://www.youtube.com/watch?v=IMN5RSIm6xw
There was GUI based debuggers.
Then there was the access of the complete OS stack and other running applications, and everything was compiled to native code, there wasn't any VM running.
Try do do a (disassemble func) on Emacs for seeing actual 80x86/ARM,....
One of the best Bret Victor talks is about that.
"The Future of Programming"
https://www.youtube.com/watch?v=8pTEmbeENF4
> And it kills me to think that Smalltalk and Visual Basic had a built-in GUI editor and layout manager, unlike the web.
Anyone of us doing desktop/mobile development on .NET, Java, Android, iOS, Qt development can still enjoy such goodies.
With web, one day it might catch 90's RAD tooling.
http://www.smashcompany.com/technology/the-problem-with-html
Android, iOS, XAML and QML are quite nice to work with.
The live aspect was great, though.
Also RAD tooling is about the whole stack, not just dragging stuff into forms.