Lack of communication

I found out that I really hate the lack of communication at work.
It is not that I am interested very much in everyone's personal life, but still - I think it is good to know some basic stuff about people - so you can start some kind of "small talk" when necessary.
Well, seems it is not so important to other people.
For example - we do share birthdays and namedays, but other nice (or not so nice) stuff is not shared.
I just learned today that two of my collegues were pregnant (wouldn't hurt if they told us:) )
When one of my collegues left - it was not officially announced.
When another one was moved to another job-position within the company - nothing.
When three new people came - also - no official presentation in front of the others.
I guess it is the HR's responsibility to do these, yet people might also dare to take the lead.
They have nothing to loose in the situation:)