I think the core issue is that the difficulty in producing good UI grows faster than linearly compared to the underlying complexity of what it represents.
Just look at the best in breed WYSIWYG editors (Word, @googledocs, whatever). There is a wealth of powerful things you could do with documents, yet they are basically the same old linked-list semantics-free dumb documents that we had in the 80s.
Building a good, new, powerful UI for documents is really hard. That’s why we still have lossy formats like Word, PDF, or LaTeX. And that’s just documents.
As @jamespearce and @brianleroux debate in the comments, there was a lot of great things that VB did. I agree! I’d love a VB for Web stuff, for those simple projects. But like WYSIWYGs it would likely remain stuck at the level of power of its time.