I do agree with you that the hierarchy ought to listen to and respond to the laity.  
I am not knowledgeable enough about Vatican politics to be sure, but from what I have read, it appears that rather than dialogue with the Pope, the signers of the two documents are hoping to embarrass him.  There are all sorts of meetings at which the hierarchs can dialogue with the Pope.  The theologians involved can write scholarly articles, thereby engaging with peers. As all professionals and scholars, they belong to professional organizations at the meetings of which their points can be productively discussed with each other and with hierarchs.  To the best of m understanding, neither document was signed by everyday lay people, so this is not truly a question of laity getting a response from hierarchs.