Easy mockery aside, a lot of employees like to gripe, and if the feedback was just the sort of useless whining that 1% of the workforce loves to engage in, then I'd shut it down too(or, possibly more maliciously, leave it up for morale and stop reading it).
It's an interesting problem. A small proportion of the complaints might be about something urgent--- how do you sort them out from the minor or irrelevant stuff?
If it's worth saying but not worth its own thread even in discussion it goes here.