Commercialization and commoditization: "Why make things better when people don't care?"
It’s just that we don’t know how. Even designing a good text based language is very challenging, and in no way a solved problem. Something graphical and interactive has a much larger design surface, and is thus even harder to get right, especially for general purpose programming.
The incentive exists for the shareholders, but they are not the ones making hiring decisions and choosing tools for programmers to use.