I recently posted this question about how to build a good bridge out basic bricks ( Bridge from just basic bricks? ), which got closed as being too open-ended, apparently. I found this to be, of course, extremely discouraging. I would suggest How to Build X type of questions are acceptable. They are fun, engaging, and don't hurt anybody.
Our community is young and traffic is still light, but I'm confident that there will be more questions like this. The issue is whether we turn users with these question away, or welcome them.
As a practical example, if my bridge question is unacceptable, then I would suggest that following must also be unacceptable:
- How to build a (automatic) Mindstorms charging-station?
- What is a good ratio to buy bricks in?
- How would you make a good pivot-arm suspension?
- How does one get a job as a LEGO designer?
Personally, I think all of the above questions positively contribute to the community - I would hate to see them go away.