Meta is a discussion site, no question about it.
In that respect, the site's purpose is kind of shoe-horned into the format, but we make it work pretty well.
That being said, the format itself does have it's own advantages!
- Native voting/polling system built right in. For example, you get almost instant feedback on a proposed feature request, or how to most effectively use your newfound editing ability when you reach 2k reputation.
- A categorization system (tags) to find the information -- and related information -- you're looking for.
- Since the format is the same, Meta is often used as a testing ground for new features.
Of course, the format has its disadvantages as well, such as limiting extended discussion, or other niceties that traditional forums have like private messaging (that's a good/bad thing I suppose).
You're right -- sometimes there isn't a "best" answer to a question on Meta. The topics on here are both highly varied and often subjective simply due to the nature of the issues we deal with. For example, while a bug report is a more or less objective topic, asking how to deal with users is more of a subjective, "soft" topic. There can still be a "best" answer produced from these topics, but it's not a requirement. (You will notice that accept rates on Meta are often lower than elsewhere.)
As I mentioned, there are advantages and disadvantages to using this format, but I think the bottom line is that if Meta didn't use this format, that says a lot about the ideal universal acceptance the management would like to see.
Even with all our subjective topics here, Meta has shown that the format can work.