I think this is a good suggestion.
Perhaps one way to solicit suggestions for a specific features would be for Mark to create a message asking for input on that subject, example:
"Looking for suggestions for wikipage editing #suggestion"
Then he could make it "sticky" so it would be at the top of the message list.
He could add as many as he wanted, 2 or 3 maybe, adding one per week and leave it there for 3 weeks so they would cycle.
There could also be a wikipage created, and maybe made sticky, that would record all the #suggestion messages by subject.
That way the first thing a visitor sees are the suggestions made and those requested.
Mark, or another Moderator could manage the page, merging posts as required.
How could Mark decide which topics to post?
A poll maybe? He and the other Moderators could get together and come up with a list of 20 possible subjects,
The purpose and "Rules" specified in the Question portion could explain the process so the poll respondents would understand what the goal is.
As the top answer gets moved to a sticky post, the Poll could be updated to include new choices, perhaps based on the spurious requests that come in.
Perhaps one of the choices would be to either explain how to restore a wikipage revision or add a "Restore the version" button