I would not favour a scheme like that. I understand the reasoning behind it, but box-filling like that is just too restrictive.
You can have them click "review" instead of "post", then they can edit the response as a whole, so that you can make the post have whatever you want (like it is now). After reviewing, you can then click "post" to submit.
To each his own, but I find having templates for people really helps clear things up for everyone. I use templates for git issues and it really, really helps. There's no reason it wouldn't help here, too.