Incoming suggestions are reviewed in the order they are received by a team of Lindens with diverse areas of expertise. We consider a number of factors: Is this change possible? Will it increase lag? Will it break existing content? Is it likely that the number of residents using this feature will justify the time to develop it? This wiki page further describes the reasoning we use: Feature Requests

We are grateful for the time you took to submit this feature request. We hope that you are not discouraged from submitting others in the future. Many excellent ideas to improve Second Life come from you, our residents. We can’t do it alone.

Thank you for your continued commitment to Second Life.