There are many subtle differences between an average leader and a great leader. Average leaders need to control the discussion within the organization. They don't want anyone questioning their authority or outwardly raising ideas that are counter to their own. Mostly they are insecure about their leadership position and are not comfortable enough in their own skin to handle criticism. You can recognize them easily as they are often heard saying, "Are you questioning my authority?"
And in their defense it is not easy to handle criticism. It takes a tough outer shell to accept constructive criticism in the positive way it is often intended by caring and involved employees. But if you can get past it, it can provide a gold mine of new ideas.
Accepting criticism can allow new ideas to percolate up from within the organization, rather than the obey or die leadership style that rules primarily with top down ideas.
My daughter recently lost her job as a part-time retail sales clerk. She was fired! The acorn doesn't fall far from the tree. She questioned authority and suggested an alternative way for the company to hold a weekly mandatory educational meeting. She wrote an incredibly respectful letter, that a significant number of her coworkers signed, that asked the company to consider positive alternatives to the company's mandatory 30-minute Saturday morning meeting.
Had she written such a letter at my company I would have made her a part of the employee education committee or figured some way to get her involved. Which would have sent the message that we encourage respectful participation in the discussion of our policies and we want those who work for us to challenge leadership if they feel we, as leaders, could be doing a better job. Instead this particular company fired the ring leader. Can you imagine the lack of open and honest dialogue the company is going to receive from their employees over the next several years? A company's culture is created by its actions that speak far louder than anything they say.