I get your desire for mass culling and it was something that I considered adding. I ultimately decided against it because I wanted to keep the slow pace of the game. It's as much, if not more, about chilling on the island with your flowers as it is about being a mad scientist. I experimented with the mad scientist angle during development, allowing the player to mass cull plants and providing them with a machine that let them breed crosses quickly, and it was fun, but just didn't hit the vibe I was going for.
Also, it's well over a year at this point since I released the game, so active development on new features is over. Unfortunately it didn't get enough traction at launch for me to be able to put the time in on those.