Since people don't seem to think that much discussion is needed, let's make this a vote.
Instructions: Vote on precisely one of the two posts below to decide whether SystemModeler-only questions should be on-topic or not. Use only upvotes, no downvotes please.
Note: Questions about how to use SystemModeler from Mathematica (e.g. WSMLink) are on-topic. This is about deciding whether SystemModeler questions not related to Mathematica will also be on-topic. An example would be a question concerned solely with Modelica code, not Mathematica code.
If you believe more discussion is needed or the decision shouldn't be made yet, post an answer.
Original post below:
It is time that a definitive decision should be reached on whether questions about SystemModeler are on-topic for Mathematica.SE. We need a meta post that clearly states the decision and can be linked to. The current uncertainty is clearly bad. People who help out with the review queues need to have a clear answer.
There was a long discussion about this, but no definitive conclusion has been reached. The highest voted answers in that discussion concludes
Weighing the pros and the cons I'd say we pick a wait-and-see approach.
After a wait of two years, it's time to re-evaluate this and reach a definite conclusion.
I was first going to make this a yes/no style vote, but I'm not convinced anymore that people wouldn't want to have some discussion, so I will not make it a vote yet.
Summary of relevant facts:
There are 9 questions tagged system-modeler, asked over a period of nearly two years.
Two of these mention Modelica code, one is about WSMLink (i.e. how to access SystemModeler from Mathematica), two are of the tech-support type (i.e. software doesn't work, can't set it up), two are closed, and the rest are general.
All questions have been answered.
There is one user, Malte Lenz, who is providing most good answers. He is one of the SystemModeler developers. It appears that current SystemModeler expertise may be lacking among MSE regulars. jrhodin, also a SystemModeler developer has also answered questions here.
Wolfram Community has 32 threads. Not all questions are answered. Some threads are not questions but usage examples or short tutorials posted by WRI.
It appears that there's clearly more SystemModeler activity on Wolfram Community, but not dramatically so. Generally, there is not a lot of visible SystemModeler activity online.
I think most people would agree that questions about how to access SystemModeler from Mathematica (WSMLink) will be on-topic. This discussion is about whether all SystemModeler questions should be on-topic (including ones concerned with Modelica code).