Hey lbarron, it takes a lot of time to do coding for free and manage the support on here – so I try to do the updates when I have time and do what I think is best for the plugin and the users.
Currently, there are lot of configurable options with the plugin and in the shortcode, so if you would use a shortcode with all the functionality the plugin offers, you would have a very complicated shortcode that is many lines long and to be honest it can be very confusing.
So the next stage of the project is to develop an admin interface which makes it really easy to build a search form, and will also make it easier to add in new features such as category including/excluding (+ many more).
But, building a whole admin interface with a really easy to use UI is not an easy task! So please be patient, all free plugin developers are donating a lot of their personal time to their plugins (if they are actively maintained) ??
Anyway, with the amount of developing hours it takes to add more features it is possible I will launch a pro version and provide better support for things like feature requests!