Group members don't like to cause discomfort to other members in order to reach their own desired results. This perceived discomfort leads individuals to be less involved. In most cases, individuals would rather withdrawal than impose discomfort on others in a group situation.
Unfortunately this means good ideas are often kept quiet until someone feels comfortable to bring them forward. Solutions to your organizations greatest problems may already exist in the minds of members who don't want to impose.
In other situations, group members have certain desires that are only appropriate (or of interest) to a few individual in the group. Members are hesitant to share their requests the whole group because of the negative feedback.
Structure your community to identify subgroups of interest where such a message would be appropriate. This way members can quickly identify and meet others who are interested in hearing from them-- increasing the positive feedback. Smaller audiences helps cultivate an idea before it's shared with a larger group.
Communities should encourage members to define the subgroup they wish to share with and provide tools which facilitate this communication. This means, ideas to improve membership don't have to start with the "membership committee" or even with executive decision makers.
Some tools to facilitate improvement while reducing individuals concerns about imposing on others include:
Message board systems-- establish an open communications policy that encourages members to discuss concerns on an open forum. This low-risk model gets new ideas on the table for others to consider, without the concern of interpersonal confrontations.
Newsletter features-- ideas suggested to a newsletter editor can be presented anonymously for the group to consider. Use your regular communications tools to ask your members to consider issues that face your organization.
Classified ads papers-- if a newsletter is cost prohibited, allow members to "own" the publication with sponsored advertisements, and contributed articles. This outlet gives a larger diverse audience more options for opinion and sharing of ideas.
Informal forums or networking events-- like message board, this low-risk environment encourages the sharing of ideas. Bring people together for informal discussion, and in conversation, individuals will share ideas that can improve your organization.
Private suggestions that provide anonymity-- encourage members to come forward with their ideas with the option to preserve anonymity. This allows an idea to be discussed without putting an individual on the spot, while giving leadership access to the original suggester. (Not an anonymous suggestion box, individuals must be responsible for clarification and implementation.)
Special interest groups-- Use small groups to focus on specific issues. Usually those who won't share ideas with the larger group will participate with a small group to solve specific problems. Require them to define clear objectives and have a time-line to address the problem investigated.