while in general, a question for Designer Reasons is allowable (currently), they have a reputation that warrants heightened attention to them. So before asking a Designer Intent question, ask yourself: Does your question fits one of these formats?
"Why did the designers make this terrible rule?"
"Is this rule's outcome intended by the game's designers?" or "Is this the RAI for this rule?"
If yes, read on, you might want to refine your question!
Often, Designer Reasons is barking up the wrong tree
If your question fits the Type 1 question in both tone and style: You are currently not asking for designer reasons and you don't actually seem to want designer reasons, you want to have validation of your dislike of a specific rule. That is opinion based and because of that, it is most likely off topic, mainly for tonal reasons. To get it on topic, ask instead in a factual manner if the designers have stated their goals or explained them!
Others fall into a danger that Type 2 questions pose: There are actually 2 different variants of the question that can be hidden in this style of asking:
2A questions are actually wanting to know if the designer explained something specific. Those are good and on topic.
However, 2B questions are different: Instead of asking if the rule interpretation is correct, they ask for the designer statements about a thing. Those latter questions are most often not about Designer Reasons at the core. Those could be reframed to make them better. If you actually want to ask such a 2B question:
Instead focus on: What problem are you trying to solve at the table?
When a rule looks weird or feels out of whack, a lot of different questions arise, one of which is "what were they thinking?"
"What they were thinking" doesn't matter in our RPG.SE context. I will quote @BESW for a good idea of why "we are here" on this stack:
We aren't here on the Stack to read the rulebooks to people. We're
here to help people learn how to synthesize the mechanics, the
non-mechanical text, the social context, our personal experience, the
learning of the broader community, to apply all that to a particular
real-life problem someone's having and find a solution for it
We need to get the question pointed at the problem to solve so that play at the table isn't impeded by a given rule or decision, rather than being pointed at discomfort with a given design decision.
Good Designer Reasons Answers use stated design goals
A good designer reason answer should use something that is publicly stated, where design goals of the game are discussed, or where changes to the game are reasoned. Interviews, errata, or even design documents are needed to back up a good answer. For example, a decent designer reason question might be:
Why were some items in maid renamed or totally rewritten from the Japanese version?
For this, there is an entire document in existence, which not only gives the direct translation from the Japanese version for all items, it also explains each and every changed thing why it was done. In most cases, it was the missing cultural context in western countries or cultural inappropriateness of certain symbolism. And of course:
So, the author [Ryo Kamiya] basically wrote this game as a huge dose of ironic humor at this whole Maid phenomenon.
As such, he used a lot of references, gags and dialogue text that can be best described as “sexy funny”.
Problem is, when we did a straight-up translation into English, some parts came out as “creepy sexy”.
- Ewen Cluney: Maid RPG
The Nun-Approved File, p.1