Number 2: it requires effort. You need to actively listen to the viewpoints of others as it not only helps you understand the topic in a broader sense but it shows you value their input (even when you completely disagree!).
Number 3: it develops your connection with others. I bang on and on about "connecting" to people. This is largely in part to my spiritual beliefs but I think it is a fundamental part of human relationships on a very primal level. A conversation allows you to resonate with another individual or individuals over mutual interest or concerns. You can learn from one conversation whether that person is trustworthy, honest, kind, open and welcoming if the conversation is conducted sufficiently.
Number 4: the ending is as vital as the beginning. Have you managed to tie up the topic with any strong solutions or have plans been put in place? Are all parties happy with the outcome? Is this a person you will likely converse with again? If so, has it been left on a happy note?
People are shit at talking these days because most of us are staring at our phones, but it is a sad day when you can't even talk to another human being because you forgot how important it was to be heard.