For the record I'm against this change (let's call it a liberalization of policy). However if this is to be adopted I strongly feel we need formal rules and "reasons to close" which at least try and prevent opening the floodgates. So ...
We're going to need a "No Prior Research" reason to close.
Welcome to the homework dumping website.
I'm afraid that this change would open us up to every single "homework-type" question that most of the sites (like Physics, Mathematics ) would reject as not having enough prior research.
Note that Physics has an explicit rule about a requirement for basic research to be done by the OP and to be demonstrated in the question. You can't just say "I tried everything" - that's not enough.
Here's what the Physics SE rule says :
"Homework-like questions should ask about a specific physics concept and show some effort to work through the problem. We want our questions to be useful to the broader community, and to future users. See our meta site for more guidance on how to edit your question to make it better"
We would need to modify that to something like :
"What-If ... ?" style questions should show some effort to research the problem before asking on Worldbuilding SE. We're happy to help users with specific issues beyond their ability, but a basic effort to seek a solution using common resources (like Wikipedia) is expected. Users need to ask questions which can provide answers of reasonable length and not simply try to offload their own research to Wordlbuilding."
We probably needs to add an explicit statement about homework.
"Homework questions are explicitly off topic. Like other SE sites we do not do homework or check answers on Woirldbuilding SE."
A more difficult question is whether we should allow questions asking about personal theories. I feel this is would be opening the floodgates to nonsense. Again Physics SE explicitly makes personal theory questions off-topic.