Jim -
This forum is a good place to make at least informal suggestions / complaints. It is read by MS staff, and as enough comments about a certain feature, or lack thereof, are noticed, they start to show up on radar.
Actually having a WLOC 'Suggestion Box' separate forum is a very good idea - allow suggestions to be seen as distinct from requests for help.
Another idea is to simply use 'Suggestion: xxxx' or 'SUGGESTION BOX: xxxx' as the title for a post - make it stand out; something like 'SUGGESTION BOX: Phishing Filter Change' for this post.
Good luck.
- FriendlyFFF