How many times you make complaints about things that you're not satisfied with in a day? If you ask, I would say quite plenty.
Psychologically we make complaints to get attention from the other side, which is by letting your voice actions and hoping they will take physical actions to address the issues you brought up. Verbal communication is any way will not be effective, that part I can guarantee.
And how many times in a day we're thankful for the good things that people did to us? If you ask, I would say almost none.
We tried to be nice to others but most of the times, we are taken for granted. If you don't believe, try smiling to strangers when you bump into them while walking and count how many will smile back to you. In developed cities like Kuala Lumpur and Singapore, people tend to be on their own and ignore the people around them. They all seemed to have lost the courtesy of life, by being nice and pleasant towards other people.
So the next time you voice out your dissatisfaction, try to back how such thing happened and is it worth making a fuss about it. If it's something that can be solved simply, you'll smile all day long and tell yourselves why make such fuss.
People can be hilarious at times when they tend to laugh at others.