RG is starting a survey asking members why they don't publish preprints. I think, in special cases it could be an advantage to publish a paper which is not ready and "mature" in all details. But in general I don't support the sudden interest of RG to get more preprint uploaders. There exists another problem of your publishing as carrier-promoting measure: The main problem in my situation is to get a license in a short time from the journal-/ or he book-publisher if you have published there some interesting research results. It endures sometimes several years until they agree to give the allowance of publishing the article or book in an open-acces online platform, like RG. That is understandable, they want to sell your literary property, and they have to fight for their own survival.
Howsoever: Other scientific online portals offer users the opportunity always to correct und to refine the script. That seems to me a good way to come from a preprint to a mature script. The problem is: RG doesn't allow this procedure. Here you are forced to delete the current version and to upload in a new process the improved version. - You may put back the old version in the "private area", but this does't touch the main problem. There I am somewhat sceptical regarding the new preprint drive of RG - What is your opinion?