I don't think that the questions should be upvoted in general as:
(a) The reward for the person asking the question is the collection of answers. If the answers aren't rewarding then the question probably didn't need to be asked in the first place.
(b) Typically the questions are short and require very little work.
However occasionally I would upvote a question if it was really thought provoking or insightful or led to information that I found to be valuable.