It would be rather inhumane to prohibit oneself or others from speaking about troublesome things.
In a broader perspective, another way of looking at complaining is to see it as vaci sankhara, meaning that one can see it as fabrications. Tracing our discontent speech back to the thoughts that causes them allows us to further investigate and take care of the suffering/dukkha that the complaining originates from.
In other words, being mindful of the reasons for our complaints allows us to exercise samma vayama, right effort.
Going back to your original question, venting discontent without deeper understanding isn't necessarily wrong speech, but it will likely maintain status quo as long as it lacks mindfulness and right effort.