You raised some good points, and it's important to handle criticism properly. Sooner or later, we end up on the receiving end of it, so we need to be considerate in how we handle it.
If we need to criticize someone, we need to be considerate about it. We point out the mistake, suggest a solution or a correction, and show humanity to the person we criticize. This is good both online and in real life.
As much as possible, we make the criticism in private; no one likes to be embarrassed or humiliated in front of people. We would want someone to do that for us when we get criticized, so it's only right we do that to someone else.
We also need to keep in mind who is doing the criticizing to us. Is it someone we love, care about, respect, or even fear? Then we need to listen and act. Is it random mobs from Web 2.0 social media? Then it's just background noise and we can let it pass over us.
If we did wrong and we get criticized, we deal with it and proceed from there. If we get criticized but we didn't do anything wrong, we cannot let that criticism pass without defending ourselves.
As much as it sucks to get criticized, it's one way we learn and improve. We should at least do it the right way.