OPINIONS --- the Joy and Bane of Worldbuilding
I've been active here for a couple years and have often, perhaps to the point of ticking some people off, argued against the Closure for Being Opinion Based rule being applied too strongly. There is a reason for the existence of this rule; and there is also a reason for ignoring this rule.
First, we are not an independent worldbuilding Q&A community. We are part of a broader community, Stack Exchange, and we have to abide by their rules, norms, expectations, etc. AS BEST WE CAN!
Stack Exchange, as a broad community, follows the basic premise that we focus on 'single problem questions' that are 'focused' and that can be factually answered. A person can ask "why did Napoleon lose at Waterloo" and get the answer "X, Y & Zed". This could theoretically be checked against standard resources, source documents, contemporaneous accounts and military reports and thus the response can readily be known to be factually correct and thus 'the single best answer'.
At Worldbuilding, we have to ignore that because our material is essentially irrealia --- things that don't actually exist and events that didn't actually happen in the real world. Thus, I argue that 99% of all questions asked here in Worldbuilding are, in fact, opinion based. You provided two non-Santa questions for consideration.
- A question on the date for colonising Venus & Mars
- A question on the correlation of a wizard's staff and his magical prowess
On the surface, both questions are asking for opinions, simply because we have colonized nothing in space and magical staves and wizards aren't real. Thus both are questions open to speculation that would not be accepted on any other Stack.
But we have to understand that in this community we bend the opinion based rule in order to do what we do. In order to do this, we have to devise our own rules and expectations as to how we bend the SE rule and what we expect from querents and respondents alike.
Why the Second Question is Okay--
The question about wizard staves is okay. I read it and this is what I find: the OP asks for our opinion, but also focuses our efforts by laying out a basic description of the fictional world being considered and by laying out the various criteria with which magic can be described. Finally, the OP asks a spcifically narrow and focused question based on a single well developed worldbuilding problem.
Why the First Question is Bad--
The question about colinisation of Venus and Mars is bad. First it's asking two different questions that I have the feeling might require different economic, mathematical & technological approaches (I'm not a rocket scientist): two planets, two approaches. Here, the OP asks again for our opinion, but there's a problem: our efforts are not focused by the OP. The OP presents us with an entirely open ended discussion type question. We are not given any specific parameters or criteria to follow. Furthermore, the possibly correct answers are almost limitless. What's the real difference between 1998, 1999, and 2000 as potential answers? The problem is that any of those numbers is simply an opinion.
Our community has decided that Opinions are okay, but they need to be sought appropriately. We have decided to reject purely aesthetic opinions like "what colour dress should a princess wear to a party" and any kind of unrestrained opinion question like "when should X happen". We also reject open ended discussion questions, fishing expeditions, brainstorming questions, etc.
All of these question types are in fact valid, and they all have a place. Stack Exchange is not that place. The kind of open ended question about Venus colonisation would be perfectly fine at Reddit, because they do not have the same high expectations that we have.
I agree with you --- both questions are "fine". I actually left some comments on the Venus colonisation query that, I hope, might lead to an improvement, or at least provide some SE related food for thought for the OP. The only problem is that what we think of as "fine" does not guarantee that it is also a good fit for this community.
"Little better than brainstorming" --- a perennial problem here! The issue here is that we do not allow pure and unrestrained brainstorming that might occur elsewhere. We require all our brainstorming efforts to be constrained by the Stack Exchange model.
"Small cabal of rules lawyers" --- welcome to the cabal! We love it when new members accept our invitation to join! Seriously, you're doing exactly what I've always asked people to do --- join in the discussion. It may very be that you'll inspire some kind of change in how WB.SE operates!
"Abandoning the rule regarding opinions" --- I think you'll find that you and I possibly agree on this issue more than you might think! I've been railing against the strict application of this rule in all its forms for years. I've found that in almost every case, the issue is one of the perspective of individuals. Some people are strict. Some people are lax. Some people feel overly empowered. Some people just don't care.
The long and short of it is this: I hold that since WB exists within the SE network, we become responsible for maintaining SE rules and norms within our community. We therefore can not actually abandon this rule on opinion based questions. If we do, then SE is well within rights to shut us down. What we can do is discuss, create and enforce our own rules and norms that will serve as work-arounds to the network wide rule.
If anything, I think that the rule as it stands is an improvement. It allows us to ask for opinions, but filters out questions that just don't fit the SE model. This is a win for us because we are doing due diligence in maintaining SE norms, but are also establishing our own norms to allow the widest array of questions we can.
"If this question was asked today, by a new user, how many of you would be voting to close it as opinion based?" --- I would not vote to close the wizard' staff question. I also note that you wrote a pretty respectable answer! I actually upvoted the query, because I think it's a good question, is useful for others, and is well composed.
I would vote to close the colonisation query because it is not well composed. I suggested a way to improve it, because I think it is an interesting question and is of potential use to others. Just not in the way it's written.