I know that at one point in the history of Stack Overflow (which this site is based on), there was a problem with the 'Ask a Question' button being too easy to find, resulting in people posting low-quality questions (ie, the questions were poorly worded, poorly researched, etc).
I don't know if this was a motivating factor in this site's design, to down-play the Ask link. I don't think this community has a problem with many drive-by askers, so I agree, the Ask link should be more prominent. If we end up having a problem down the line, perhaps we can revisit this then.