The easiest way to ask a theme author questions is to submit comments on the theme’s page. (The only way too maybe?) If the question has already been asked it is difficult and time consuming to look through all the comments and find it, hence I doubt many people do it. As more comments are added this becomes even more prohibitive.
If instead of comments the layout was designed as a forum it would be a much easier process for all involved. The author could sticky posts that are frequently asked (or post a faq). Other customers could answer each other’s questions—some of these are very simple and could be answered so quickly without having to take up the author’s time. I know that’s part of the work of creating a template, but this would encourage more of a community and would lead to more productivity. Plus, using the forum design, the number of repeat questions the author would have to be answering could be kept to a minimum.
This is an annoyance that I’ve noticed with the Themeforest setup for a while and is one of the major factors that is really holding the site back from being what it could be.