The 90's also saw much commercial experimentation with visual environments (e.g. Visual Basic, Delphi, JBuilder) with round-trip conversion between the layout form and underlying code. They were promoted for R.A.D. (rapid application development -- remember that acronym?) but, like dynamically typed languages, they also had sustainability issues.
Of course, like dynamic typing and Lisp, visual environments also had Smalltalk from way back, but they were before big business became infatuated with the ideas.
How do products like Delphi have sustainability (maintainability ?) issues ? Delphi/Object Pascal is statically-typed, so you can't even build an application that has issues with the code-behind for a form.
You can see errors at run-time from mismatches between the code-behind and the forms, but this has nothing to do with the language. It's just the way that certain products like Delphi decided to handle such mismatches. You'll see these types of issues with any code that performs run-time serialization/deserialization of class instances. Our product, Elevate Web Builder, uses a similar architecture with its WYSIWYG form designer/forms (they use JSON instead of a custom key-value format), but it simply ignores properties in forms that don't exist in the actual code.
Of course, like dynamic typing and Lisp, visual environments also had Smalltalk from way back, but they were before big business became infatuated with the ideas.