Criticism is rampant in any group you are connected with, especially the Church. You put a few Christians in a room and give them enough time, and someone will start to complain. It might be about the facilities, the lesson material, the teacher, or the other people in the room.
What is fascinating to me is that if you listen closely, you will find that when one person complains, then another will join in and then another until everyone has issues with the situation.
There are numerous reasons that this dynamic plays out in groups of people. One is because we want to connect to other people emotionally. If we are unequipped to do that, we quickly resort to our basic instincts. We display our dislike of something and share a complaint, knowing that someone will connect to us through our negative emotions. That means people complain to connect to others in a meaningful way.
One sign of maturity in your faith is when you quit using negative feelings as your bond to others and start using positive. You can walk into a room and start saying all the positive things you see and feel. This will generate others to share the good things they see. Soon everyone is feeling closer without the ugly residue leftover after criticism.
All of us want to connect to others emotionally, the easiest way is through negativity, but the most fulfilling way is through positivity. Both of these outlooks will make friends; just know that one group will eventually level their complaints against you.