Thanks for the review!

I do however think you've missed the idea of this plugin. This plugin was created out of necessity for a survival server as I can tell you a majority of players ain't going to denyspawn individual hostile mobs as most simply dont know how. However flagging a region with a simple allow/deny can be done very easily.
Also adding to that, Many of the servers player base was already actively switching mob-spawning to allow to breed/spawn passive mobs. This plugin was made so a player can set it once and continue playing as normal without hostile mobs spawning and without constantly switching as needed allowing for a better player experience.

I hope that you now understand its intended use and will reconsider your 3 star review.