Hi there,
Currently, that how it behave actually as we design it to shown inline instead of row by row as those design(row by row, like module) might become lengthy and very long, considering you have a lot, very lot of categories and sub-categories.
Perhaps it would be best if you can submit a feature request regarding this issues by creating a new ticket on the forums and set it to "Feature Request" so that everyone else could vote for it. We will prioritize this feature during the development process for the next major version of Easyblog if there are more people request on this.
Thanks for your understanding.