"Little of what's meant is understood"...True, the reader has to be sympathetic to the stance of the writer and understand the language used. A few words may contain unfamiliar phrases, errors, twists, barbs and references to things which the reader is unaware of.
"Is this communication?"...It is if what is meant is understood by the reader.
"Do you want to understand?"..Tricky. Everybody wants to understand what they are already open to. They will not want to understand ideas that are at odds with their chosen world view or do not support their idea of what is real.
"Do you want to be understood?"...Personally, not always. Sometimes I will throw in such an obscure reference that nobody appears to see it. Sometimes this gives me a feeling of success. Being understood on here is not as essential as it is in daily life.
"Do I want to communicate?"...I guess I must do, otherwise I would not be typing ths answer. The irony is that frequently I am communicating on here whilst ignoring the efforts of the real people right next to me.
"Why would somebody not want to?"..Introverts may avoid the effort of communication, those who have things to hide may not want to give themselves away, those who have poor social skills or education may feel they will be mocked. I am sure there are many more reasons.
There is no doubt that communication is important. Our whole society is built on the transfer of information and the flow of ideas. Yet it is something we take for granted as just being there.