I think there are two problems here, both of which could be chipped away at, but neither will be completely solved anytime soon.
First, you have the fact that users don't know enough to solve abstract problems with programming. As programmers we have this deep base knowledge that we subconsciously draw upon. It's impossible to create a platform that makes it trivially easy to "test small game ideas" without narrowing the scope to trivial game types. People need a foundation to figure out how to put the pieces together. Fortunately, a lot of this is just familiarity with computers, so every new generation gets better at this, making the problem more tractable over time.
The other, is that software is truly an organic ecosystem. There is no designer that is coordinating the software world. The closest we have are closed platforms like Apple provides (which is still limited in overall scope) or standards (which are defined in a deliberately narrow scope for modularity's sake). So to make a single uniform environment that could do everything a casual programmer might want to do, and make it consistent, you'd have to write some kind of monolithic standard and convince a large minority of all software writers to support it in some fashion. The UNIX philosophy and POSIX are attenots to do something like this, but as you alluded to, it's still highly non-trivial to get your footing underneath you. To create an even higher-level standard seems almost impossibly difficult, but I suppose it's possible that progress could be made by focusing purely on a new high-level language and GUI. I'm not holding my breath though.