I have this question after reading an article of Dmitry Fadeyev, the designer of ux.SE (Designing UX Exchange) (I was linked to his blog in this question). In his blog, he wrote:
Because it’s a new community, it’s important to get people to ask questions and participate. For this reason the “Add Question” button needed its own styling to stand and attract the eye.
I recall that in some sites, the Ask Question buttons don't stand out from other buttons, and therefore don't get much attractive. Is this because in these sites we don't encourage people to ask?
Some examples:
And the meta.SE as you can see it for yourself.