Should the "Ask A Question" page encourage the poster to upload their blend and also provide a means to do so? So often we have to ask OP to post their blend somewhere, but I think it'd save OP & us a lot of time & energy if we made it obvious that seeing the blend is often essential in solving the issue. If we need a file host, developer.blender.org has one so maybe we could use theirs.
Not all questions require a .blend, however for most trouble shooting questions (e.g. "Why is X happening?") a .blend is the easiest way to go.
I don't actually have any demographics (I couldn't find a good way to search for trouble shooting questions), but I think that less than half of our questions are trouble shooting questions worthy of a .blend.
I think that if we do add a notice to the ask question page, then we should say that it's probably only important if they have a trouble shooting question.
My only other concern is that it might deter users who can't or don't want to share their .blends.
I think this would be a great addition to Blender.SE. But as Gandalf pointed out, it's not always relevant to the question. But maybe we can make it very obvious that uploading is optional. (Maybe only give the option for certain tags. Or have the uploading-field grayed out/opacity reduced)
Or maybe take a different approach. What if we can have a "vote for/ask for .blend"? So the people that are answering can request a .blend. Then the OP will be notified and given instructions on how to upload (or encouraged to upload more info/screenshots, if he can't upload blend).
That way, we can automate the process. It'll be easier for us to give a solution when we need a .blend file. Also, it'll be easier for OP to upload(especially if the uploading process is similar to uploading images. Just choose blend from computer, but you don't need to redirect to pasteall.org. Blend-file is automatically added to post, at the bottom.)
In my opinion, yes. If for no other reason than to cut back on all the images that get uploaded in the process of troubleshooting a problem.
I personally wouldn't make it a requirement, but i would make it an obvious and highly encouraged possibility (perhaps even a pop-up prompt)
EDIT: the only major drawback would be that blend files can get large if they include alot of textures / sounds / videos