Clearly you don’t want to give up your own idea of a story in order to accommodate another writer’s idea. If you’re willing to do that then you might as well go around doing all the stories that non-writers perpetually offer to writers. “You know what you should write? You should write about my grandfather <or other relative, friend, favorite pet, or self> who <insert long boring monolog>.”
But it really helps to get some feedback, and sometimes that feedback can take a story in a different direction than I had originally thought, ways that I like.
So where do you draw the line?