I think there are 2 groups of customers to consider if you want to sell an affordable game dev technology (like Unity, GS, C4, Torque, Shiva, Leadwerks):

- hobby users
- experienced developers with commercial projects

Hobby users want to have fun, want to learn and want to have fast feedback. So they need good tutorials, easy to use tools, fast response (play it while developing it) and they want an easy way to generate the final game. They are interested in already prepared effects, shaders and some model and texture libraries. So they need a good and documented studio.
They will not look at technical features like scene-management, lighting-approaches or speed. Often they even dont know some of these concepts.
This is what Gamestudio and Unity advertises. This is what FPS maker does perfectly.

Experienced developers will look at features, options to extend the technology, power, speed and available platforms to increase the final success.
In the end the project matters. If they want to make a 2d game, then they would use TGB, they would use Wintermute for a 2.5d game and for casual 3d games on different platforms they would prefer Unity, Shiva or Torque3d. For a bigger project with a team, bigger game worlds and scene management they use C4.

What about Gamestudio? It is very similar to Unity, it is designed to be a good value for beginners and pro users. To satisfy the beginners, it needs an aggregated tool (med, wed, sed and real-time editor in one application). It needs some very good documentation, and an integrated new material editor with real-time feedback and shader support.

To satisfy the pro users it needs some optimization, an indoor scene-management (e.g. portals and zones) and more available platforms for publishing.
At the moment it is a good choice for friends of scripting, for web-developers, experienced with HTML, JavaScript and similar, people who are not experienced enough with C++, C#. They will like LiteC and will feel comfortable. In most cases they will be hobby users. And they could easily wander to Unity.

So it is indeed a dangerous situation and GS needs a niche, like TGB with its 2d approach. It needs a feature to prove that it is unique at the market.

I think the makers of game dev suites can learn a lot from 3d modelling and rendering applications. There is a similar situation: many hobby users and some pro users. The ease of use of these tools steadily improved. Documentation and video tutorials are often integrated parts of new features.