This question was raised on MSO [here](http://meta.stackexchange.com/questions/69675/allow-new-users-to-post-comments-against-questions) and Jeff declined it. From his answer [here](http://meta.stackexchange.com/questions/69675/allow-new-users-to-post-comments-against-questions/69686#69686)

> As it says in the /faq, new users can post comments on *their own* questions and answers, as well as any answers to questions they own.
>
Beyond that you can refer to my previous answer on this topic.
>
[New users can't ask for clarification except as answer](http://meta.stackexchange.com/questions/51926/new-users-cant-ask-for-clarifications-except-as-answers/51939#51939)

Further to this, any question that attracts a lot of "new" attention will generally be flagged and protected to disallow users posting to it unless they have 10 reputation. We are working hard to get users out of the forum mindset, and into the Q&A mindset. Anything that encourages forum behavior is bad, especially on a site like Super User. We are strict for a reason, since we are driving **high quality** content which other sites do not offer.