So are they worried that it's not governed and controlled by a central organization, because this is the reason why people adopted it in the first place. 

They feel safe, when they can control it, and there in the problem, BTC do not want to be controlled, it's protocol was designed to eliminate manipulation by central entities.

Once it's centralized and controlled, people will not use it, and they will invent the next technology, not controlled by central entities.