Interesting idea but it'll need some work. Let's say I have a problem - it takes too long to get from point a to point b. Do I propose a solution to the problem or just post the problem? If it's the former, my suggested solution may be too far reaching or not far reaching enough (teleportation vs make faster cars). If it's the latter, it may be easy to get people to agree a problem exists but hard to get them to agree on what a good solution would be.
Of the two, the latter is probably the better option. Perhaps I list a pain point along with the amount I'd be willing to pay to have that problem solved. Others do the same. There's no tipping point because it's unlikely that by simply having a problem I'd also know how much it would cost to solve the problem.
At any point, users/companies with the skills to solve the problem can propose solutions along with their minimum funding requirements and relevant credentials. I can select more than 1 solution and whichever solution reaches their minimum funding requirements first gets my pledge.
Or instead of trying to compete with kickstarter, this could simply be a step that happens before campaigns are launched on KS. People list their pain points and the amount they'd be willing to pay to have them solved and then you charge companies to add their solution/link to their KS campaign.