Hi, i'm the developer of the Q3D plugin.
I understand the dream you have. I love the design of constructs programming interface, and would love to have it for something 3D, and that's why i'm currently developing the plugin. Right now it's very basic and many people misunderstand the complexity of 3D games and expect making one will be anywhere as easy as making a 2D one. Everything Ashley is saying is completely true, 2D engines are much more widely accessible because of the fact drawing is such a basic skill, and the fact most math you're going to use for common things doesn't really require anything beyond high school trigonometry. He's not really insulting anyone's intelligence by claiming most people construct is aimed at wont have studied the more complicated math and sub systems involved yet. He's simply stating construct is meant to appeal to a demographic which doesn't really overlap the demographic who are capable of working in 3D.
I think i'll be able to somewhat achieve the goal of "easy" 3D using construct, but there are always caveats. People will need to understand that lighting and shader building, preprocessing of lighting, the vector math and linear algebra and every complicated trick which is situation specific and complicated about 3D cannot be simply tucked away under the hood as an automatic process which the engine will take care of. In a way my goal is to move towards doing that with future updates for Q3D, but as it stands now the plugin is meant to enable 3D and nothing more. Doing what you're asking for in its entirety is very much easier said than done. 3D games require careful engineering in order to perform properly in a variety of different situation. There are a lot of challenges i face in developing a plugin to make 3D work for an audience that will have very high expectations about performance and ease of use.
I think you aren't really looking deeply enough into the repercussions if scirra officially focus on making their tool support 3D. A lot of people could unanimously agree that Construct is an incredible 2D game engine, really the best around. If they were to focus on adding in 3D or a new 3D tool, that would mean they really wouldn't be able to keep making it the best 2D game engine around. They would have to put an incredible amount of effort to get something okay, and people would likely be unhappy because the reality of 3D game development would clash with their expectations. There's no point for them to stop working on a fantastic 2D tool, to make an alright 3D one, which would really never compete very strongly with better established 3D tools like unity or engines like Unreal.
I think the devs should focus on making the Construct SDK better so that more people can make construct do more things than it currently can. Right now extending functionality through the editor isn't possible, and we're left to basically only have some basic object parameters to control everything. the ability to do more complex drawing and operations in the layout, launch popup windows to organize properties better akin to custom "image editors" etc. would be a great step in making higher quality plugins possible.