I am not so sure if too much participation by non-experts or laymen, even more so when talking about research priority settings, really is a good idea. In particular concerning fundamental (physics or generally fundamental) science questions, the average Joe from the street possesses often neither enough knowledge nor the true interest to be entitled to decide about future research questions and directions ...
In fact, for fundamental physics the involvement of people who have no sufficient technical understanding but a personal agenda and negative personal opinion about certain research fields have been able cause some non-trivial overall damage which can be measured by from a scientific point of view not justified losses of funding, positions, etc ...