This is a nice option that would lower the barrier for newcomers.
I am not sure it is such a good idea though: usually if someone doesn't use the preview, doesn't see that their post doesn't look right and doesn't try to fix it, I see that as a sign that they do not really care about getting answers to their question(s). Or that they are just rude, "here is something that must be a question, figure out how to read it and then answer it, I have no time to loose following the obvious link to Writeup Formatting Tips". So why should we move the burden from them (to post properly) to the server (as the reload would increase its load)?
I haven't been a newby here in a while ;--) but really, is it that difficult to figure how to write a properly formated post? That's a real question BTW