What do you think those reasons are? In case of HyperCard I think it's that there wasn't any inter-stack-linking let alone networking.
What I'm crying about is that Smalltalk was not the future.
It's too hard/expensive to make that kind of abstracted GUI that lets you make real software, and too hard to keep it updated as the environments/contexts change, as in your example of networking became important, and it wasn't part of hypercard, and would have taken a lot of time and skill to make it so in a useful way.
It's just too hard. You can make that kind of layer for a special special purpose domain (say, making simple games, or sound engineering, or what have you), but it's hard even to do that right, let alone a general purpose universal environment. Software is expensive enough to develop with quality the 'ordinary way', let alone trying to develop and maintain some kind of layer on top that let's people do it without.... without what? Without knowing what they're doing? At some point, if you are able to make it actually powerful enough, it's going to be just as 'hard' as anything else, isn't it?
HyperCard failed, but not necessarily for technical reasons.
It might be worth making some hypotheses and testable predictions here about how much complexity is needed for various tasks, and how well current tools are doing at avoiding unnecessary complexity.
I think surveying the current landscape and past efforts, and getting a dialog going along the way, would be a lot more valuable than immediately starting to design a solution.
I'm very confident there are opportunities here, but not so confident about the chances of any particular approach.