TL;DR:
If you want 3D supported here, Post good 3D design questions.
(... and not software support questions)
Here is the thing....
I'm all for 3D questions as they relate to design. But find me one here which is design related and references Maya, Lightwave, etc. All I see are software support questions. Which we have plenty of.
We customarily do allow 3D questions that relate to design. But we tend to close (rightly so) questions which ask how to use an application as related to 3D apps or technical support. The same way we tend to close video questions.
I realize 3D is a broad and sweeping thing and it means different things to different people. As I've posted before there is indeed some crossover between 3D modeling and graphic design. I do not deny that. But there's also crossover between automobile engineering and graphic design, commercial constructions and graphic design, environmental design and graphic design, etc.
The truth of the matter almost anything can also touch on some aspect of graphic design. After all everything we see in life has been designed. So, where's the line? What would be off-topic.
I'll go with however the community decides to go. I'd just caution against opening a door to an area so vast that it has the ability of overshadow every other area. Do we really need more "how do I use Maya" or "How to fix 3DS" questions?
There's no need for "3d" as a topic to be allowed. If a question is design related, we already allow it even if the user happens to be using some 3D application. The problem is... we don't get design questions as they relate to 3D applications. We get tech support questions for 3D apps and as far as I'm aware we are not a software support stack in spite of the abundant Adobe questions we get. But we do close roughly 80% of the Adobe questions which are along the same lines as all the 3D questions we've gotten.
The 3D proposal at Area 51 failed for a reason. Not enough support. So if there's so little interest in that stack... why clutter this site with more of the same lazy questions from those users?
Please, post some examples of 3D questions which would be beneficial to this site. Because that seemed impossible at the Area 51 proposal.
Too much focus is being placed on the names of 3D applications. A good design question is a good design question and the software in use is irrelevant. Post a good design question and it won't matter that a 3D app is being used. But disallowing software support questions for 3D application is really not too much in my opinion.
In the end... if this site is to be a software support site, then fine be one. Otherwise, we need to stop focusing on what apps are or are not allowed and focus on the intent of questions as they relate to design. Thus far, I've only ever seen software support questions for 3D apps here.
If you want 3D to gain support here... Post good 3D design questions.