I'm apologize in advance for necroing this with a response.
If we limit ourselves to simple, objective questions that can have a definitive answer, we will limit our range of topics on important topics to programmers. Much of what makes a good programmer good is not his/her technical mastery of a given language or API, but rather his/her judgement and skills in organizing code.
These types of skills/judgements are, by definition, subjective. A question like "How should I design XYZ type of program" is subjective, by definition. However, questions like this are more often than not more informative than "how do I use printf to format something like so?" Even if the question is subjective, and is not provably correct, some answers will be better, and show more insight than others. Some people will consistently give answers that demonstrate more insight.
These are exactly the kinds of people that I want to see with high reputations. If I want a description of an API, I'll get a book, read the documentation, or just fire up a compiler.
And, even if there is discussion back-and-forth between two viewpoints (both of which may be legitimate), reading that discourse can only help educate others on the appraoches suggested, the models used, and the advantages and disadvantages of each. Which would you rather have access to, Knuth and Djikstra giving answers to questions that could be resolved by reading a spec, or them debating opposite points of view on program design? Which would be more valuable, more informative?
Yes, some questions may become argumentative. "What's better, C# or C++?" But even in this flamebait question there's room for illumination - a good answer would point out that both languages serve different purposes, suggest where they may be more or less-well suited (and why), and give the asker an idea of the strengths and weaknesses of each. My experiences have been that an answer like that would quickly be upvoted, and weaker answers ("C++ because it's lower level and good programmers use low-level languages") would either be downvoted or just ignored.
Additionally, even "cut and dried," apparently objective answers often have a significant subjective component to them. A simple question of "how do I do X with Y" might trigger someone with experience to point out that the question is itself a design smell, and points to an underlying problem that can be approached from a different angle. This type of answer, IMHO, is better than the mechanical description of how to do the actual task asked. Part of being a good developer is digging for the real requirements, and answering a question on SO is much the same. So, the line between "subjective" and "objective" is a mighty thin one anyway.
Yes, there are other questions "What's your favorite programmer comic" that are just chat questions. Fine, community-wiki those. Sometimes joke answers are made - fine, community-wiki those, too.
But all 'subjective' questions do not fit that category. And they are, in many cases the more important questions to be asked and answered. It is that higher level thought that I'd really want to see more of. And I'd like to see the people capable of providing it rewarded and recognized.
If I really need to know about operator precedence in C++, I'll read the spec.