I was stuck with that for a long time.
Here is the key.. do lot more reading.
Park the thought of writing for a while and start to read articles that interest you to the fullest(Say to yourself - this day is only for reading). Read the entire article without leaving a single point. While reading, it can happen that something strikes your mind or you dis-agree with that writing or there is another view the author has missed. Keep developing those thoughts and one day you will feel content upon finishing a great hub.
You will then comeback and vote this up!!(Just kidding)
While hopping hubs, I will read a great article and realize that you wrote it(This can be true!!)
Also, with more reading, you will be able to judge the quality of writings, which in turn helps in judging your own content. May be, this is for later!
Just an analogy that can ring some bell in you : I am a software developer. I know how to write code. If I drag myself to write code, I will do something, but its is good for none including me. Then, I started to go around to see others' code/software and realized that there can be some room for improvement. I am content with what I am coding now. In some time, I will be doing something new rather than extending something that already exists. Pretty long, but hope it helps!!