I am of the belief that writing could be improved by editing. The trouble is getting the idea down on paper so that it could be improved later. First drafts are just that, first drafts, they need to go through many iterations to improve.

Writing has the function of tangible thinking as well, it is when one is writing that we realise we think in certain ways or that we don't know certain things as we imagined.

For me, this would help in forcing me to write something without waiting for the perfect sentence to form in my mind.