Although it can be fun to include in our stories all the things we imagine happening to our characters, often this results in writing ourselves into a corner. Or worse. We write purposefully towards an event with no regard as to whether it fits into the overall scheme of things. This can result in a manuscript being filled with a series of meaningless, unrelated events that do nothing to help your character on their journey. Everything that happens in your story should be relevant, important and meaningful to your protagonist, and either move them closer towards achieving their goals or hinder their efforts.
If you don’t consider the relevance of your ideas and the reason you want to include them now, at this stage of the story-writing process, you run the risk of becoming too attached to them after having written them into the story. By then, it will be much harder to “kill your darlings” and the revision process will become much more difficult.