I am not sure that they are simply for show.  I think that the enotes points values you see represent the level of interest or, dare I say, scholarship of participating individuals on the site.  For example, in any given category or title, you can see on the right hand side point values for leading voices in that particular category.  This will help you gauge the person who is answering your question.  I think that you can take it on faith that if someone is answering your question, and they have a great deal of points accrued in that category, the answer you receive will probably have some merit.  One of the challenges with so many online answering sites is that one simply does not know.  There is ambiguity as to who is answering your question.  The points markers on enotes helps you understand that the person answering your question might have had familiarity with other questions in that category.  This means that their base of knowledge is fairly strong and that the answer you receive could have some level of greater validity.  I am not sure you can trade in your points for anything, but given the recent redesign of the site, that might not be a bad idea, at all.  For the most part, though, I see the points featured as representative of the people answering questions out there and the more points that they have earned, the better the chance that their answers could be quite relevant to you in your quest to find answers.