"Premise bunny" is such a good term. FWIW, there are quite a few techniques from (original) fiction writing that are used to water and fertilize premise bunnies so they grow into plot bunnies (and then outlines, and then 1st drafts). Until I started learning which of those techniques work for me, I had many original fiction premise bunnies that refused to grow into something useful, manageable, and writable. Back when I was deeply frustrated with the application of a particular technique (hero's journey) on an original novel-in-progress, I switched to writing fanfic (2007) and used fanfic as a way to try out eight different approaches/techniques for turning premises into full-on plot structures. Using someone else's world and/or characters proved useful because it kept those aspects constant (saving me time/energy) while I learned different plotting techniques and compared/contrasted them with each other.