I've been kicking around a few related thoughts for a while. Let me see if I can put them in some sort of order. I'll start with the last piece that came to me:
Complaining signifies weakness. To complain is to express the desire for a thing to be otherwise than it is. The complainer himself may or may not possess the power to make the thing the way he wants it. If he lacks the power, his complaint signifies weakness directly; if he has the power, it signifies weakness indirectly, in that he either lacks or did not properly apply the power to prevent the thing from becoming what he didn't want in the first place.
Strength is for succoring the weak. By Divine will, we're all in this together. As St. Catherine of Siena saw, the way we do good to God is by doing good to our neighbors. And we do good to our neighbors by making up from our strengths what they lack in their weaknesses. The parable of the sheep and the goats makes this clear: if we don't do what is within our power to do for the powerless, we go to hell.
If you aren't weak, don't complain. If complaining signifies weakness, and strength is for succoring the weak, then to complain is to impose an obligation under charity upon those who hear the complaint. In fulfilling that obligation, they may be unable to respond to other instances of weakness. Complaining, then, is not something that should be done lightly; in particular, it shouldn't be done by someone who doesn't want some sort of help from those who hear the complaint.
Complaining does have a social component. Complaining can signify more than weakness; it's often used to strengthen social bonds within a group of similarly-weak peers. In this case, the help sought is precisely the strengthening of those bonds.
It can be hard to tell the weak from the strong.
This last point is the subject of most of my thought on all this. I see a lot of strong people trampling on weak people. Bruised reeds are there for the breaking, it seems, particularly among those who view tensions within the Church in militaristic terms. If you're fighting a war -- of culture, of liturgy, of ideas -- then it only makes sense to strike where the enemy is weak.
But what if the enemy isn't the ones with a particular weakness? What if the enemy is the weakness itself?
Then, I'd say, two things follow. First, people who are weak should not be treated as enemies. Second, we'd better make sure the people we do treat as enemies aren't people who are weak.
My impulse is to assume that anyone I perceive as trampling on a weak person is himself strong, and so I may treat him as a strong person. To a strong person, I can say, "Hey, you! Stop trampling on that weak person!"
But my impulsive assumption is, in general, false. Someone trampling on someone else may well be weak -- his very habit of trampling may be his weakness. In that case, for me to treat him as a strong person could be for me to trample on his weakness, to treat this bruised reed as though he were an oak tree.
So I'm in a bit of a fix. On the one hand, I firmly support a "No Bellyaching" rule; I think there are too many complainers who can, and therefore ought to, shut their pie hole and suck it up.
On the other hand, I have no way of knowing who, in particular, is breaking that rule. Well, other than me; in the words of the poet, "I can't complain, but sometimes I still do."
What's left for me to do, then, is to propose the rule:
Don't bellyache. i.e., Don't complain just for pleasure.
Then leave the enforcing of it to each person individually.